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 *
  FMR LLC
 2. Date of Event Requiring Statement (Month/Day/Year)
03/29/2011		 3. Issuer Name and Ticker or Trading Symbol
IRONWOOD PHARMACEUTICALS INC [IRWD]
(Last)
(First)
(Middle)
82 DEVONSHIRE STREET, 		 4. Relationship of Reporting Person(s) to Issuer
(Check all applicable)
_____ Director __X__ 10% Owner
_____ Officer (give title below) __X__ Other (specify below)
Edward C. Johnson 3d
 5. If Amendment, Date Original Filed(Month/Day/Year)
(Street)

BOSTON, MA 02109		 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)
Class A Common Stock 1,225,178
D
 
Class A Common Stock 1,150,135
I
By Impresa Fund II LLC
Class A Common Stock 74,798
I
By Impresa Fund III Limited Partnership
Class A Common Stock 10,971
I
By Fidelity Biosciences Corp.
Class A Common Stock 1,224,933
D
 

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

Reporting Owners

Reporting Owner Name / Address Relationships
Director 10% Owner Officer Other
FMR LLC
82 DEVONSHIRE STREET
BOSTON, MA 02109		     X   Edward C. Johnson 3d
FIL Ltd
PEMBROKE HALL
42 CROW LANE
HAMILTON, D0 		     X   Edward C. Johnson 3d

Signatures

Scott C. Goebel, Duly authorized under Powers of Attorney effective as of June 1, 2008, by and on behalf of FMR LLC and its direct and indirect subsidiaries, by and on behalf of Edward C. Johnson 3d, and by and on behalf of FIL Limited. 04/08/2011
**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).
 
Remarks:
Remark 1:  In addition to the securities shown in Table 1, Fidelity Management & Research Company, a wholly owned subsidiary of FMR LLC and an investment adviser registered under the Investment Advisers Act of 1940, is the beneficial owner of 1,349,274 Class A Common Stock, or 2.776% of the Class A Common Stock of Ironwood Pharmaceuticals Inc. as a result of acting as investment adviser to various investment companies registered under the Investment Company Act of 1940.  FMR LLC, Edward C. Johnson 3d and FIL Limited have no pecuniary interest in the 1,349,274 Class A Common Stock.

Remark 2:  FMR LLC directly holds 1,225,178 Class A Common Shares and FIL Limited directly holds 1,224,933 Class A Common Shares of Ironwood Pharmaceuticals Inc.   FMR LLC and FIL Limited are of the view that they are not acting as a "group" for purposes of Section 16(a) under the Securities Exchange Act of 1934 and that they are not otherwise required to attribute to each other the "beneficial ownership" of securities "beneficially owned" by the other corporation within the meaning of Rule 16a-1 promulgated under the Securities Exchange Act of 1934.  Therefore, they are of the view that the shares held by the other corporation need not be aggregated for purposes of Section 16(a).  However, FMR LLC is making this filing on a voluntary basis as if all of the shares are beneficially owned by FMR LLC and FIL Limited on a joint basis.

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