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* Abingworth LLP (Last) (First) (Middle) 38 JERMYN STREET (Street) LONDON X0 SW1Y 6DN (City) (State) (Zip)	2. Date of Event Requiring Statement (Month/Day/Year) 10/28/2014	3. Issuer Name and Ticker or Trading Symbol Sientra, Inc. [ SIEN ]
		4. Relationship of Reporting Person(s) to Issuer (Check all applicable) Director X 10% Owner Officer (give title below) Other (specify below)	5. If Amendment, Date of Original Filed (Month/Day/Year)
			6. Individual or Joint/Group Filing (Check Applicable Line) X Form filed by One Reporting Person 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)
Common Stock	1,704,012	I	See Note(1)(2)

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

Explanation of Responses:

1. Consists of (i) 852,006 shares held of record by Abingworth Bioventures V LP, or ABV V, and (ii) 852,006 shares held of record by Abingworth Bioventures V Co-Invest Growth Equity Fund LP., or AGE. ABV V and AGE are collectively referred to as the "Abingworth Funds." The investment manager of the Abingworth Funds is Abingworth LLP, or Abingworth. Abingworth Bioventures V GP LP or Abingworth GP, a Scottish limited partnership, serves as the general partner of each of the Abingworth Funds. Abingworth General Partner V LLP, a Scottish limited liability partnership, serves as the general partner of Abingworth GP. Abingworth GP (acting by its general partner Abingworth General Partner V LLP) has delegated to Abingworth all investment and dispositive power over the shares held by the Abingworth Funds. The reporting person holds the reported securities indirectly through Abingworth.

2. The reporting person is part of an investment committee of Abingworth, which approves investment and voting decisions by a majority vote, and no individual member has the sole control or voting power over the shares held by the Abingworth Funds. The reporting person disclaims beneficial ownership of all shares held of record by the Abingworth Funds. This report shall not be deemed an admission that the reporting person, Abingworth or any other person is the beneficial owner of the securities reported herein for purposes of Section 16 of the Securities Exchange Act of 1934, as amended, or for any other purpose.

	/s/ John Heard	10/28/2014
	** 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).
** Intentional misstatements or omissions of facts constitute Federal Criminal Violations See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
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