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

OMB APPROVAL OMB Number: 3235-0104 Expires: January 31, 2005 Estimated average burden hours per response... 0.5

(Print or Type Responses)

1. Name and Address of Reporting Person *   Haines Timothy 2. Date of Event Requiring Statement (Month/Day/Year) 10/28/2014 3. Issuer Name and Ticker or Trading Symbol Sientra, Inc. [SIEN] (Last) (First) (Middle) C/O ABINGWORTH LLP,, 38 JERMYN STREET 4. Relationship of Reporting Person(s) to Issuer (Check all applicable) __X__ Director __X__ 10% Owner _____ Officer (give title below) _____ Other (specify below) 5. If Amendment, Date Original Filed(Month/Day/Year) (Street) LONDON, X0 SW1Y 6DN 6. Individual or Joint/Group Filing(Check Applicable Line) _X_ Form filed by One Reporting Person ___ 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 1,704,012 I refer to footnotes 1 and 2 (1) (2)

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.			SEC 1473 (7-02)
	Persons who respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB control number.

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
Haines Timothy C/O ABINGWORTH LLP, 38 JERMYN STREET LONDON, X0 SW1Y 6DN	  X	  X	Â	Â

Signatures

/s/ Joel Smith, Attorney-in-fact for Timothy Haines		10/28/2014
**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)	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.
  Remarks: Exhibit 24- Power of Attorney for Timothy Haines.

Note: File three copies of this Form, one of which must be manually signed. If space is insufficient, See Instruction 6 for procedure.

Potential persons who are to respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB number.