SEC Form 3

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 or Section 30(h) of the Investment Company Act of 1940

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1. Name and Address of Reporting Person* FMR LLC (Last) (First) (Middle) 82 DEVONSHIRE STREET (Street) BOSTON MA 02109 (City) (State) (Zip)	2. Date of Event Requiring Statement (Month/Day/Year) 03/29/2011	3. Issuer Name and Ticker or Trading Symbol IRONWOOD PHARMACEUTICALS INC [ IRWD ]
		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 of Original Filed (Month/Day/Year)
			6. Individual or Joint/Group Filing (Check Applicable Line) Form filed by One Reporting Person X Form filed by More than One Reporting Person

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

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: 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

1. Name and Address of Reporting Person* FMR LLC (Last) (First) (Middle) 82 DEVONSHIRE STREET (Street) BOSTON MA 02109 (City) (State) (Zip) Relationship of Reporting Person(s) to Issuer Director X 10% Owner Officer (give title below) X Other (specify below) Edward C. Johnson 3d

1. Name and Address of Reporting Person* FIL Ltd (Last) (First) (Middle) PEMBROKE HALL 42 CROW LANE (Street) HAMILTON D0 (City) (State) (Zip) Relationship of Reporting Person(s) to Issuer Director X 10% Owner Officer (give title below) X Other (specify below) Edward C. Johnson 3d

Explanation of Responses:

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.

	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
Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
* If the form is filed by more than one reporting person, see Instruction 5 (b)(v).
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