Form N-Q

UNITED STATES
SECURITIES AND EXCHANGE COMMISSION
Washington, DC 20549

FORM N-Q


QUARTERLY SCHEDULE OF PORTFOLIO HOLDINGS OF REGISTERED MANAGEMENT INVESTMENT COMPANY

Investment Company Act file number         811-21579         

        Nuveen Floating Rate Income Opportunity Fund         
(Exact name of registrant as specified in charter)


        333 West Wacker Drive, Chicago, Illinois 60606         
(Address of principal executive offices) (Zip code)


Jessica R. Droeger—Vice President and Secretary
        333 West Wacker Drive, Chicago, Illinois 60606         
(Name and address of agent for service)

Registrant's telephone number, including area code:         312-917-7700        

Date of fiscal year end:            07/31          

Date of reporting period:          04/30/05         

Form N-Q is to be used by management investment companies, other than small business investment companies registered on Form N-5 (§§ 239.24 and 274.5 of this chapter), to file reports with the Commission, not later than 60 days after the close of the first and third fiscal quarters, pursuant to rule 30b1-5 under the Investment Company Act of 1940 (17 CFR 270.30b1-5). The Commission may use the information provided on Form N-Q in its regulatory, disclosure review, inspection, and policymaking roles.

A registrant is required to disclose the information specified by Form N-Q, and the Commission will make this information public. A registrant is not required to respond to the collection of information contained in Form N-Q unless the Form displays a currently valid Office of Management and Budget (“OMB”) control number. Please direct comments concerning the accuracy of the information collection burden estimate and any suggestions for reducing the burden to the Secretary, Securities and Exchange Commission, 450 Fifth Street, NW, Washington, DC 20549-0609. The OMB has reviewed this collection of information under the clearance requirements of 44 U.S.C. § 3507.

Item 1. Schedule of Investments

Portfolio of Investments (Unaudited)
Nuveen Floating Rate Income Opportunity Fund (JRO)
April 30, 2005
        Weighted                 
Principal        Average    Stated    Ratings*         
Amount (000)    Description(1)    Coupon    Maturity*    Moody's    S&P    Value 
 
 
    VARIABLE RATE SENIOR LOAN INTERESTS(2) - 132.9% (80.7% of total assets)                     
    Aerospace & Defense - 2.4% (1.5% of total assets)                     
$ 9,500    K & F Industries, Inc., Term Loan B    5.569%    11/18/12    B2    B+    $ 9,671,195 
 
 
    Airlines - 2.8% (1.7% of total assets)                     
10,916    United Air Lines, Inc., DIP Term Loan (Tranche B) (a)    7.500%    9/30/05    N/R    N/R    10,988,626 
 
 
    Auto Components - 4.0% (2.4% of total assets)                     
3,234    Accuride Corporation, Term Loan    5.356%    1/31/10    B2    B+    3,236,330 
5,499    Federal-Mogul Corporation, Revolver (a)(d)    4.660%    2/05/05    N/R    N/R    4,673,469 
4,000    Goodyear Tire & Rubber Company, Second Lien Term Loan (b)    5.890%    4/30/10    B2    B+    3,973,572 
1,000    Goodyear Tire & Rubber Company, Term Loan (b)    4.840%    4/30/10    Ba3    BB    1,003,125 
3,000    Goodyear Tire & Rubber Company, Third Lien Term Loan (b)    6.640%    3/01/11    B3    B-    2,857,500 
 
 
                        15,743,996 
 
 
    Beverages - 1.4% (0.9% of total assets)                     
5,541    Dr. Pepper/Seven UP Bottling Group, Inc., Term Loan B    5.320%    12/19/10    B1    N/R    5,639,272 
 
 
    Building Products - 4.1% (2.5% of total assets)                     
1,499    Masonite Corporation, Canadian Term Loan (b)    7.250%    3/21/13    B2    BB+    1,501,065 
4,501    Masonite Corporation, Term Loan B (c)    6.750%    5/13/11    B2    BB+    4,508,310 
9,950    Nortek, Inc., Term Loan B    5.340%    8/27/11    B2    B    10,093,031 
 
 
                        16,102,406 
 
 
    Chemicals - 6.0% (3.6% of total assets)                     
1,054    Celanese Holdings LLC, Delayed Draw Term Loan (d)    0.750%    4/06/11    N/R    B+    16,685 
4,443    Celanese Holdings LLC, Term Loan C    5.625%    4/06/11    B1    B+    4,526,533 
1,383    Headwaters Incorporated, Term Loan B    5.400%    4/30/11    B1    B+    1,403,814 
5,000    Huntsman International LLC, Term Loan    6.050%    3/31/10    B1    B    5,082,500 
2,414    Huntsman International LLC, Term Loan B-1    5.500%    12/31/10    Ba3    B    2,456,451 
10,000    Rockwood Specialties Group, Inc., Tranche D    5.430%    7/30/12    B1    B+    10,128,125 
 
 
                        23,614,108 
 
 
    Commercial Services & Supplies - 4.5% (2.7% of total assets)                     
3,405    Allied Waste North America, Inc., Letter of Credit    3.100%    3/21/12    B1    BB    3,415,834 
9,195    Allied Waste North America, Inc., Term Loan B    5.180%    3/12/21    B1    BB    9,226,463 
4,970    National Equipment Services, Inc., Term Loan    8.970%    8/17/10    B3    B    5,075,574 
 
 
                        17,717,871 
 
 
    Containers & Packaging - 5.6% (3.4% of total assets)                     
12,968    Graham Packaging Company, L.P., Term Loan B    5.650%    10/07/11    B2    B    13,155,068 
2,000    Graham Packaging Company, L.P., Term Loan C    7.313%    3/15/12    B2    CCC+    2,052,250 
611    Smurfit-Stone Container Corporation, Deposit-Funded Commitment    2.100%    11/01/11    Ba3    BB-    622,486 
4,873    Smurfit-Stone Container Corporation, Term Loan B    4.800%    11/01/11    Ba3    BB-    4,955,998 
1,499    Smurfit-Stone Container Corporation, Term Loan C    4.920%    11/01/11    Ba3    BB-    1,524,923 
 
 
                        22,310,725 
 
 
    Diversified Telecommunication Services - 5.4% (3.3% of total assets)                     
1,500    Fairpoint Communications, Inc., Term Loan    5.170%    2/15/12    B1    BB-    1,519,125 
1,995    Intelsat, Ltd., Term Loan B    4.630%    7/06/11    B1    BB+    2,011,459 
8,500    Iowa Telecommunications Services, Inc., Term Loan B    5.084%    11/23/11    Ba3    BB-    8,595,625 
8,000    Qwest Corporation, Term Loan A    7.390%    6/30/07    Ba3    BB-    8,242,500 
980    Valor Telecommunications Enterprises, LLC, Term Loan    5.075%    2/14/12    Ba3    BB-    992,250 
 
 
                        21,360,959 
 
 
    Electric Utilities - 6.4% (3.9% of total assets)                     
7,037    Allegheny Energy Supply Company, LLC, Term Loan    5.610%    3/08/11    Ba3    BB-    7,105,742 
5,970    Calpine Construction Finance Company, L.P., Term Loan B    8.860%    8/31/09    B1    B+    6,223,409 
2,000    Murray Energy Corporation, Term Loan C    10.640%    1/28/11    N/R    N/R    2,095,000 
2,923    Texas Genco LLC, Delayed Term Loan    5.060%    12/14/11    Ba2    BB    2,949,263 
7,059    Texas Genco LLC, Term Loan    5.009%    12/14/11    Ba2    BB    7,122,471 
 
 
                        25,495,885 
 
 
    Food & Staples Retailing - 1.8% (1.1% of total assets)                     
6,955    The Jean Coutu Group Inc., Term Loan B    5.500%    7/30/11    B1    BB    7,069,650 
 
 
    Food Products - 1.7% (1.0% of total assets)                     
6,500    Dole Holding Company, LLC, Term Loan    8.000%    7/22/10    B3    B    6,751,875 
 
 
    Gas Utilities - 4.3% (2.6% of total assets)                     
5,625    El Paso Corporation, Deposit-Funded Commitment    2.290%    11/23/09    B3    B-    5,663,281 
9,300    El Paso Corporation, Term Loan    2.290%    11/23/09    B3    B-    9,378,14 
2,000    Regency Gas Services LLC, Term Loan C    8.780%    12/01/10    B3    B-    2,030,000 
 
 
                        17,071,424 
 
 
    Healthcare Equipment & Supplies - 2.3% (1.4% of total assets)                     
6,000    Cooper Companies, Inc., Term Loan B    4.563%    10/20/11    Ba3    BB    6,078,750 
3,193    Kinetic Concepts, Inc., Term Loan B-2    4.850%    8/11/10    Ba3    BB    3,243,558 
 
 
                        9,322,308 
 
 
    Healthcare Providers & Services - 8.8% (5.3% of total assets)                     
5,587    Alderwoods Group, Inc., Term Loan B-2    4.876%    9/29/08    B1    BB-    5,673,919 
7,294    Community Health Systems, Inc., Term Loan    4.640%    8/19/11    Ba3    BB-    7,383,977 
5,459    IASIS Healthcare LLC, Term Loan B    5.370%    6/22/11    B1    B+    5,552,002 
1,000    Lifepoint Hospitals Holdings, Inc., Term Loan B    4.584%    9/30/11    Ba3    BB    1,003,125 
2,993    Vanguard Health Holding Company, LLC, Initial Sub Tranche 2 Term Loan    6.350%    9/23/11    B2    B    3,052,350 
11,940    Vanguard Health Holding Company, LLC, Term Loan B    6.340%    9/23/11    B2    B    12,175,069 
 
 
                        34,840,442 
 
 
    Hotels, Restaurants & Leisure - 7.0% (4.3% of total assets)                     
2,987    24 Hour Fitness Worldwide, Inc., Term Loan B    6.250%    7/01/09    B1    B    3,035,887 
10,000    OpBiz, LLC, Term Loan A (c)    6.100%    8/31/10    B3    B-    10,043,750 
1,282    Venetian Casino Resort, LLC, Delayed Draw Term Loan (d)    0.750%    6/15/11    B1    B+    5,609 
6,218    Venetian Casino Resort, LLC, Term Loan    4.810%    6/15/11    B1    B+    6,262,252 
3,857    Wyndham International, Inc., Revolving Credit III (d)    0.500%    6/30/06    N/R    N/R    (5,785) 
8,545    Wyndham International, Inc., Term Loan I    7.688%    6/30/06    Caa1    B    8,567,829 
 
 
                        27,909,542 
 
 
    Household Durables - 4.1% (2.5% of total assets)                     
8,451    Jarden Corporation, Term Loan    5.088%    1/24/12    B1    B+    8,502,521 
7,590    Sealy Mattress Company, Term Loan D    4.940%    4/06/12    B1    B+    7,633,894 
 
 
                        16,136,415 
 
 
    Household Products - 2.5% (1.5% of total assets)                     
9,925    Prestige Brands, Inc., Term Loan B    5.380%    4/06/11    B1    B+    10,069,546 
 
 
    Insurance - 2.2% (1.3% of total assets)                     
8,630    Conseco, Inc., Term Loan    6.564%    6/22/10    B2    BB-    8,799,113 
 
 
    IT Services - 4.2% (2.5% of total assets)                     
16,650    Fidelity National, Term Loan B    4.651%    3/09/13    Ba3    BB    16,608,375 
 
 
    Machinery - 1.6% (1.0% of total assets)                     
6,296    Dresser-Rand Group Inc., Term Loan    5.360%    10/10/10    B1    B+    6,396,833 
 
 
    Media - 27.0% (16.4% of total assets)                     
16,347    Advertising Directory Solutions Inc., Term Loan B    5.070%    11/09/11    B1    BB-    16,412,078 
11,000    Alliance Atlantis Communications Inc., Term Loan    4.760%    12/20/11    Ba2    BB    11,065,313 
2,500    American Lawyer Media, Second Lien Term Loan    10.500%    2/24/11    Caa1    CCC    2,509,375 
7,500    Century Cable Holdings, LLC, Discretionary Term Loan (a)    7.750%    12/31/09    N/R    N/R    7,430,625 
9,000    Century Cable Holdings, LLC, Revolver (a)    6.750%    10/25/10    N/R    N/R    8,860,784 
12,000    Charter Communications Operating, LLC, Term Loan A    6.190%    4/27/10    B2    B    11,841,138 
1,990    Charter Communications Operating, LLC, Term Loan B    6.440%    4/07/11    B2    B    1,970,697 
7,848    Loews Cineplex Entertainment Corporation, Term Loan B    5.199%    6/30/11    B1    B    7,979,227 
5,000    Metro-Goldwyn-Mayer Studios, Inc., Term Loan B    5.380%    4/12/12    N/R    N/R    5,011,720 
10,917    Panamsat Corporation, Term Loan B    5.310%    8/20/11    Ba3    BB+    11,079,878 
8,718    R.H. Donnelley Inc., Tranche D    4.800%    6/30/11    Ba3    N/R    8,838,983 
5,000    Rainbow Media Holdings LLC, Term Loan    5.690%    3/31/12    N/R    N/R    5,075,520 
3,970    Regal Cinemas Corporation, Term Loan    5.093%    11/10/10    Ba3    BB-    4,033,019 
4,955    WMG Acquisition Corp., Term Loan    5.320%    2/27/11    B1    B+    5,001,403 
 
 
                        107,109,760 
 
 
    Metals & Mining - 2.5% (1.5% of total assets)                     
6,787    Amsted Industries Incorporated, Term Loan B    5.900%    10/15/10    B1    BB-    6,896,035 
3,000    Trout Coal Holdings, LLC, Second Lien Term Loan    9.750%    3/14/12    N/R    N/R    3,061,875 
 
 
                        9,957,910 
 
 
    Multi-Utilities & Unregulated Power - 2.3% (1.4% of total assets)                     
875    NRG Energy, Inc., Credit-Linked Deposit    2.993%    12/24/11    Ba3    BB    886,047 
1,122    NRG Energy, Inc., Term Loan    5.250%    12/20/11    Ba3    BB    1,136,355 
6,983    Reliant Energy, Inc., Term Loan    6.040%    4/30/10    B1    B+    6,991,228 
 
 
                        9,013,630 
 
 
    Oil & Gas - 1.3% (0.8% of total assets)                     
4,988    Celero Energy, LP, Term Loan    9.355%    10/01/10    N/R    N/R    5,081,016 
 
 
    Paper & Forest Products - 1.9% (1.1% of total assets)                     
5,433    Boise Cascade Holdings, LLC, Term Loan D    4.740%    3/29/11    Ba3    N/R    5,491,574 
2,000    White Birch Paper Company, Second Lien Term Loan    12.250%    3/31/13    B3    B-    2,012,500 
 
 
                        7,504,074 
 
 
    Pharmaceuticals - 0.8% (0.5% of total assets)                     
3,000    Talecris Biotherapeutics Inc., Term Loan B    6.170%    3/31/10    N/R    N/R    3,015,000 
 
 
    Real Estate - 7.5% (4.6% of total assets)                     
1,826    Crescent Real Estate Funding XII, L.P., Term Loan    5.110%    3/20/06    N/R    N/R    1,841,625 
15,151    General Growth Properties, Inc., Term Loan B    5.100%    11/12/08    Ba2    BB+    15,274,562 
12,740    LNR Property Corporation, Term Loan    5.810%    2/03/08    B2    B+    12,808,085 
 
 
                        29,924,272 
 
 
    Software - 1.1% (0.7% of total assets)                     
4,500    Corel Corporation, First Lien Term Loan    7.220%    1/27/10    N/R    N/R    4,500,000 
 
 
    Textiles & Apparel - 3.6% (2.2% of total assets)                     
14,061    Jostens IH Corp., Term Loan C    5.190%    7/29/10    B1    B+    14,286,226 
 
 
    Trading Companies & Distributors - 1.8% (1.1% of total assets)                     
6,970    Ashtead Group Public Limited Company, Term Loan    5.063%    11/12/09    N/R    BB-    7,070,194 
 
 
    Total Variable Rate Senior Loan Interests (cost $524,510,189)                    527,082,648 
 
 
Principal            Stated    Ratings**         
Amount (000)    Description(1)    Coupon    Maturity    Moody's    S&P    Value 
 
 
    CORPORATE BONDS - 25.9% (15.7% of total assets)                     
    Diversified Telecommunication Services - 3.3% (2.0% of total assets)                     
8,000    Qwest Corporation    6.625%    9/15/05    Ba3    BB-    8,080,000 
5,000    Qwest Corporation    6.125%    11/15/05    Ba3    BB-    5,025,000 
 
 
                        13,105,000 
 
 
    Food & Staples Retailing - 2.5% (1.5% of total assets)                     
10,000    Stater Brothers Holdings, Floating Rate Note, 3.500% plus three-month LIBOR    6.710%    6/15/10    B1    BB-    9,900,000 
 
 
    Hotels, Restaurants & Leisure - 6.8% (4.1% of total assets)                     
2,750    Harrahs Entertainment    7.875%    12/15/05    Ba1    BB+    2,818,750 
8,315    MGM Grand    7.250%    10/15/06    Ba1    BB+    8,585,238 
3,785    MGM Mirage    9.750%    6/01/07    Ba2    BB-    4,097,263 
6,765    Park Place Entertainment    7.875%    12/15/05    Ba2    BB-    6,908,756 
4,440    Park Place Entertainment    8.500%    11/15/06    Ba1    BB+    4,706,400 
 
 
                        27,116,407 
 
 
    Household Durables - 0.3% (0.2% of total assets)                     
1,000    D.R. Horton, Inc.    9.375%    7/15/09    Ba1    BB+    1,051,624 
 
 
    Machinery - 3.4% (2.1% of total assets)                     
13,167    Navistar International, Series B    9.375%    6/01/06    Ba3    BB-    13,627,845 
 
 
    Media - 6.5% (3.9% of total assets)                     
18,000    Cablevision Systems Corp, Floating Rate Note, 4.500% plus six-month LIBOR    7.909%    4/01/09    B3    B+    18,450,000 
7,000    WMG Acquisition Corp., Floating Rate Note, 4.375% plus three-month LIBOR    7.585%    12/15/11    Caa2    B-    7,245,000 
 
 
                        25,695,000 
 
 
    Oil & Gas - 3.1% (1.9% of total assets)                     
11,620    Tesoro Petroleum Corporation    8.000%    4/15/08    Ba2    BBB-    12,230,050 
 
 
    Total Corporate Bonds (cost $104,055,422)                    102,725,926 
 
 
 
Shares (000)    Description(1)                    Value 
 
 
    WARRANTS - 0.0% (0.0% of total assets)                     
    Multi-Utilities & Unregulated Power - 0.0% (0.0% of total assets)                     
26    Reliant Energy, Inc.                    155,356 
 
 
    Total Warrants (cost $184,678)                    155,356 
 
 
Principal                         
Amount (000)    Description(1)                    Value 
 
 
    HIGH-GRADE SHORT-TERM INVESTMENTS - 1.5% (0.9% of total assets)                     
$ 5,994    State Street Bank Euro Dollar Time Deposit, 2.700%, 5/02/05                    5,993,725 
 
 
    Total High-Grade Short-Term Investments (cost $5,993,725)                    5,993,725 
 
 
    Total Investments (cost $634,744,014) - 160.3% (97.3% of total assets)                    635,957,655 
 
 
    Other Assets Less Liabilities - 0.2%                    802,979 
 
 
    Preferred Shares, at Liquidation Value (60.5)%                    (240,000,000) 
 
 
    Net Assets Applicable to Common Shares - 100%                    $396,760,634 

(1)    All percentages shown in the Portfolio of Investments are based on net assets applicable to Common 
    shares unless otherwise noted. 
 
(2)    Senior Loans in which the Fund invests generally pay interest at rates which are periodically adjusted by 
    reference to a base short-term, floating lending rate plus an assigned fixed rate. These floating lending rates 
    are generally (i) the lending rate referenced by the London Inter-Bank Offered Rate ("LIBOR"), or (ii) the 
    prime rate offered by one or more major United States banks. 
 
    Senior Loans may be considered restricted in that the Fund ordinarily is contractually obligated to receive 
    approval from the Agent Bank and/or Borrower prior to the disposition of a Senior Loan. 
 
*    Senior Loans in the Fund's portfolio generally are subject to mandatory and/or optional prepayment 
    Because of these mandatory prepayment conditions and because there may be significant economic 
    incentives for a Borrower to prepay, prepayments of Senior Loans in the Fund's portfolio may occur. As a 
    result, the actual remaining maturity of Senior Loans held in the Fund's portfolio may be substantially less 
    than the stated maturities shown. The Fund estimates that the actual average maturity of the Senior Loans 
    held in its portfolio will be approximately 18-24 months. 
 
**    Ratings below Baa by Moody's Investor Service, Inc. or BBB by Standard & Poor's Group are considered 
    to be below investment grade. 
 
(a)    At or subsequent to April 30, 2005, this issue was under the protection of the federal bankruptcy court. 
 
(b)    Purchased on a when-issued or delayed delivery basis. 
 
(c)    Portion purchased on a when-issued or delayed delivery basis. 
 
(d)    Position represents an unfunded loan commitment outstanding at April 30, 2005. The Fund had unfunded 
    loan commitments of $6,461,246 at April 30, 2005. 
 
N/R    Investment is not rated. 

Income Tax Information     
 
The following information is presented on an income tax basis. Differences between amounts for financial     
statement and federal income tax purposes are primarily due to timing differences in recognizing certain     
gains and losses on investment transactions and recognition of premium amortization.     
 
 
At April 30, 2005, the cost of investments was $636,415,195.     
 
Gross unrealized appreciation and gross unrealized depreciation of investments at April 30, 2005,     
were as follows:     
 
Gross unrealized:     
 Appreciation    $3,752,934 
 Depreciation    (4,210,474) 
 
Net unrealized appreciation (depreciation) of investments    $ (457,540) 

Item 2. Controls and Procedures.

  1. The registrant's principal executive and principal financial officers, or persons performing similar functions, have concluded that the registrant's disclosure controls and procedures (as defined in Rule 30a-3(c) under the Investment Company Act of 1940, as amended (the "1940 Act") (17 CFR 270.30a-3(c))) are effective, as of a date within 90 days of the filing date of this report that includes the disclosure required by this paragraph, based on their evaluation of the controls and procedures required by Rule 30a-3(b) under the 1940 Act (17 CFR 270.30a-3(b)) and Rule 13a-15(b) or 15d-15(b) under the Securities Exchange Act of 1934 (17 CFR 240.13a-15(b) or 240.15d-15(b)).
  2. There were no changes in the registrant's internal control over financial reporting (as defined in Rule 30a-3(d) under the 1940 Act (17 CFR 270.30a-3(d)) that occurred during the registrant's last fiscal quarter that have materially affected, or are reasonably likely to materially affect, the registrant's internal control over financial reporting.

Item 3. Exhibits.

File as exhibits as part of this Form a separate certification for each principal executive officer and principal financial officer of the registrant as required by Rule 30a-2(a) under the 1940 Act (17 CFR 270.30a-2(a)), exactly as set forth below: EX-99 CERT Attached hereto.


SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934 and the Investment Company Act of 1940, the registrant has duly caused this report to be signed on its behalf by the undersigned, thereunto duly authorized.

(Registrant)         Nuveen Floating Rate Income Opportunity Fund        

By (Signature and Title)*          /s/ Jessica R. Droeger--Vice President and Secretary        

Date         06/29/05        

Pursuant to the requirements of the Securities Exchange Act of 1934 and the Investment Company Act of 1940, this report has been signed below by the following persons on behalf of the registrant and in the capacities and on the dates indicated.

By (Signature and Title)*         /s/ Gifford R. Zimmerman--Chief Administrative Officer (principal executive officer)        

Date         06/29/05        

By (Signature and Title)*         /s/ Stephen D. Foy--Vice President and Controller (principal financial officer)        

Date         06/29/05        

* Print the name and title of each signing officer under his or her signature.