Ownership Submission
FORM 3
UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

INITIAL STATEMENT OF BENEFICIAL OWNERSHIP OF SECURITIES

Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934, Section 17(a) of the Public Utility Holding Company Act of 1935 or Section 30(h) of the Investment Company Act of 1940
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(Print or Type Responses)
1. Name and Address of Reporting Person *
  BAKER JULIAN
2. Date of Event Requiring Statement (Month/Day/Year)
03/10/2014
3. Issuer Name and Ticker or Trading Symbol
IDERA PHARMACEUTICALS, INC. [IDP]
(Last)
(First)
(Middle)
667 MADISON AVENUE, 21ST FLOOR
4. Relationship of Reporting Person(s) to Issuer
(Check all applicable)
__X__ Director _____ 10% Owner
_____ Officer (give title below) _____ Other (specify below)
5. If Amendment, Date Original Filed(Month/Day/Year)
(Street)

NEW YORK, NY US 10065
6. Individual or Joint/Group Filing(Check Applicable Line)
___ Form filed by One Reporting Person
_X_ Form filed by More than One Reporting Person
(City)
(State)
(Zip)
Table I - Non-Derivative Securities Beneficially Owned
1.Title of Security
(Instr. 4)
2. Amount of Securities Beneficially Owned
(Instr. 4)
3. Ownership Form: Direct (D) or Indirect (I)
(Instr. 5)
4. Nature of Indirect Beneficial Ownership
(Instr. 5)
Common Stock 171,548
I
See Footnotes (1) (4)
Common Stock 1,406,423
I
See Footnotes (2) (4)
Common Stock 35,105
I
See Footnotes (3) (4)

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly. SEC 1473 (7-02)
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Table II - Derivative Securities Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security
(Instr. 4)
2. Date Exercisable and Expiration Date
(Month/Day/Year)
3. Title and Amount of Securities Underlying Derivative Security
(Instr. 4)
4. Conversion or Exercise Price of Derivative Security 5. Ownership Form of Derivative Security: Direct (D) or Indirect (I)
(Instr. 5)
6. Nature of Indirect Beneficial Ownership
(Instr. 5)
Date Exercisable Expiration Date Title Amount or Number of Shares
Common Stock Warrant ( right to buy) 05/02/2013 05/07/2018 Common Stock 2,250,846 $ 0.47 I See Footnotes (1) (4)
Common Stock Warrant ( right to buy) 05/02/2013 05/07/2018 Common Stock 17,626,445 $ 0.47 I See Footnotes (2) (4)
Common Stock Warrant ( right to buy) 05/02/2013 05/07/2018 Common Stock 439,036 $ 0.47 I See Footnotes (3) (4)
Common Stock Warrant ( right to buy) 05/02/2013 05/07/2020 Common Stock 1,752,291 $ 0.01 I See Footnotes (1) (4)
Common Stock Warrant ( right to buy) 05/02/2013 05/07/2020 Common Stock 13,722,245 $ 0.01 I See Footnotes (2) (4)
Common Stock Warrant ( right to buy) 05/02/2013 05/07/2020 Common Stock 341,791 $ 0.01 I See Footnotes (3) (4)
Common Stock Warrant ( right to buy) 09/25/2013 09/25/2020 Common Stock 465,230 $ 0.01 I See Footnotes (1) (4)
Common Stock Warrant ( right to buy) 09/25/2013 09/25/2020 Common Stock 3,620,051 $ 0.01 I See Footnotes (2) (4)
Common Stock Warrant ( right to buy) 09/25/2013 09/25/2020 Common Stock 90,694 $ 0.01 I See Footnotes (3) (4)
Common Stock Warrant ( right to buy) 02/05/2014 02/10/2021 Common Stock 172,406 $ 0.01 I See Footnotes (1) (4)
Common Stock Warrant ( right to buy) 02/05/2014 02/10/2021 Common Stock 1,938,274 $ 0.01 I See Footnotes (2) (4)
Common Stock Warrant ( right to buy) 02/05/2014 02/10/2021 Common Stock 48,070 $ 0.01 I See Footnotes (3) (4)

Reporting Owners

Reporting Owner Name / Address Relationships
Director 10% Owner Officer Other
BAKER JULIAN
667 MADISON AVENUE, 21ST FLOOR
NEW YORK, NY US 10065
  X      
BAKER BROS. ADVISORS LP
667 MADISON AVENUE, 21ST FLOOR
NEW YORK, NY US 10065
  X      
BAKER FELIX
667 MADISON AVENUE, 21ST FLOOR
NEW YORK, NY US 10065
  X      
Baker Bros. Advisors (GP) LLC
667 MADISION AVENUE 21ST FLOOR
NEW YORK, NY US 10065
  X      
667, L.P.
667 MADISON AVENUE 21ST FLOOR
NEW YORK, NY US 10065
  X      
14159, L.P.
667 MADISION AVENUE, 21ST FLOOR
NEW YORK, NY US 10065
  X      
Baker Brothers Life Sciences LP
667 MADISON AVENUE, 21ST FLOOR
NEW YORK, NY US 10065
  X      

Signatures

/s/ Julian C. Baker 03/12/2014
**Signature of Reporting Person Date

BAKER BROS. ADVISORS LP Name: Scott L. Lessing, Title: President /s/ Scott L. Lessing 03/12/2014
**Signature of Reporting Person Date

/s/ Felix J. Baker 03/12/2014
**Signature of Reporting Person Date

BAKER BROS. ADVISORS (GP) LLC Name: Scott L. Lessing, Title: President /s/ Scott L. Lessing 03/12/2014
**Signature of Reporting Person Date

Baker Bros. Advisors LP, Mgmt. Co. and Inv. Adviser to 667, L.P., pursuant to authority granted by Baker Biotech Capital, L.P., GP to 667, L.P. Name: Scott L. Lessing, Title: President /s/ Scott L. Lessing 03/12/2014
**Signature of Reporting Person Date

Explanation of Responses:

* If the form is filed by more than one reporting person, see Instruction 5(b)(v).
** Intentional misstatements or omissions of facts constitute Federal Criminal Violations. See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
(1) As a result of their ownership interest in Baker Biotech Capital (GP), LLC, Julian C. Baker and Felix J. Baker may be deemed to have an indirect pecuniary interest in the shares of Common Stock of Idera Pharmaceuticals Inc. (the "Issuer") reported in Table I and Warrants reported in Table II directly held by 667, L.P. ("667"), a limited partnership of which the sole general partner is Baker Biotech Capital, L.P., a limited partnership of which the sole general partner is Baker Biotech Capital (GP), LLC, due to Baker Biotech Capital, L.P.'s right to receive an allocation of a portion of the profits from 667.
(2) As result of their ownership interest in Baker Brothers Life Sciences Capital (GP), LLC, Julian C. Baker and Felix J. Baker may be deemed to have an indirect pecuniary interest in the Issuer's shares of Common Stock reported in Table I and Warrants reported in Table II directly held by Baker Brothers Life Sciences, L.P. ("Life Sciences") a limited partnership of which the sole general partner is Baker Brothers Life Sciences Capital, L.P., a limited partnership of which the sole general partner is Baker Brothers Life Sciences Capital (GP), LLC, due to Baker Brothers Life Sciences Capital, L.P.'s right to receive an allocation of a portion of the profits from Life Sciences.
(3) As result of their ownership interest in 14159 Capital (GP), LLC, Julian C. Baker and Felix J. Baker may be deemed to have an indirect pecuniary interest in the Issuer's shares of Common Stock reported in Table I and Warrants reported in Table II directly held by 14159, L.P. ("14159") a limited partnership of which the sole general partner is 14159 Capital, L.P., a limited partnership of which the sole general partner is 14159 Capital (GP), LLC, due to 14159 Capital, L.P.'s right to receive an allocation of a portion of the profits from 14159.
(4) Baker Bros. Advisors LP (the "Adviser") serves as the Investment Adviser to the Funds. In connection with the services provided by the Adviser, the Adviser receives an asset-based management fee that does not confer any pecuniary interest in the securities held by the Funds. Baker Bros. Advisors (GP) LLC (the Adviser GP") is the Adviser's sole general partner. Julian C. Baker and Felix J. Baker are principals of the Adviser GP. The Adviser has complete and unlimited discretion and authority with respect to the investment and voting power of the securities held by the Funds. The general partners of the Funds relinquished to the Adviser all discretion and authority with respect to the investment and voting power of the securities held by the Funds. Julian C. Baker, Felix J. Baker, the Adviser GP and the Adviser disclaim beneficial ownership of the securities held directly by the Funds except to the extent of their pecuniary interest therein, and this report shall not be deemed an admission that any of Julian C. Baker, Felix J. Baker, the Adviser GP or the Adviser is a beneficial owner of such securities for purposes of Section 16 or any other purpose.
 
Remarks:
Julian C. Baker and Dr. Kelvin Neu, respectively a principal and an employee of the Baker Bros. Advisors LP (the "Adviser") are directors of Idera Pharmaceuticals (the "Issuer"). For purposes of Section 16 of the Securities Exchange Act of 1934, as amended the Reporting Persons are deemed directors by deputization by virtue of their representation on the Board of the Issuer.

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