FORM 4 Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 STATEMENT OF CHANGES IN 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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1. Name and Address of Reporting Person * ORBIMED ADVISORS LLC   2. Issuer Name and Ticker or Trading Symbol AMARIN CORP PLC\UK [AMRN] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) __X__ Director _____ 10% Owner _____ Officer (give title below) _____ Other (specify below) (Last) (First) (Middle) 767 THIRD AVENUE, 30TH FLOOR 3. Date of Earliest Transaction (Month/Day/Year) 04/21/2011 (Street) NEW YORK,, NY 10017 4. If Amendment, Date 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 (City) (State) (Zip) Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned

1.Title of Security (Instr. 3) 2. Transaction Date (Month/Day/Year) 2A. Deemed Execution Date, if any (Month/Day/Year) 3. Transaction Code (Instr. 8) 4. Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5) 5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4) 6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4) 7. Nature of Indirect Beneficial Ownership (Instr. 4) Code V Amount (A) or (D) Price Ordinary Shares (1) 04/21/2011   S   247,633 (2) D $ 16.18 (6) 2,426,667 I See Footnotes (3) (4) Ordinary Shares (1) 04/21/2011   S   2,367 (5) D $ 16.18 (6) 23,333 I See Footnote (4) Ordinary Shares (1) 04/21/2011   S   495,267 (2) D $ 16.91 (7) 1,931,400 I See Footnotes (3) (4) Ordinary Shares (1) 04/21/2011   S   4,733 (5) D $ 16.91 (7) 18,600 I See Footnote (4)

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Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned
(e.g., puts, calls, warrants, options, convertible securities)

1. Title of Derivative Security (Instr. 3)

2. Conversion or Exercise Price of Derivative Security

3. Transaction Date (Month/Day/Year)

3A. Deemed Execution Date, if any (Month/Day/Year)

4. Transaction Code (Instr. 8)

5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4, and 5)

6. Date Exercisable and Expiration Date (Month/Day/Year)

7. Title and Amount of Underlying Securities (Instr. 3 and 4)

8. Price of Derivative Security (Instr. 5)

9. Number of Derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4)

10. Ownership Form of Derivative Security: Direct (D) or Indirect (I) (Instr. 4)

11. Nature of Indirect Beneficial Ownership (Instr. 4)

Code

V

(A)

(D)

Date Exercisable

Expiration Date

Title

Amount or Number of Shares

Reporting Owners

Reporting Owner Name / Address	Relationships
	Director	10% Owner	Officer	Other
ORBIMED ADVISORS LLC 767 THIRD AVENUE, 30TH FLOOR NEW YORK,, NY 10017	X
OrbiMed Capital GP III LLC 767 THIRD AVENUE, 30TH FLOOR NEW YORK,, NY 10017	X
ISALY SAMUEL D 767 THIRD AVENUE, 30TH FLOOR NEW YORK,, NY 10017	X

Signatures

/s/ Samuel D. Isaly		04/25/2011
**Signature of Reporting Person		Date

Explanation of Responses:

*	If the form is filed by more than one reporting person, see Instruction 4(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)	The Ordinary Shares (the "Shares") may be represented by American Depositary Shares, each of which currently represents one Ordinary Share.
(2)	These Shares are directly owned by OrbiMed Private Investments III, LP ("OPI III") and may be deemed to be indirectly beneficially owned by OrbiMed Capital GP III LLC ("Capital"), OrbiMed Advisors LLC ("Advisors") and Samuel D. Isaly ("Isaly"). Capital is the sole general partner of OPI III. Advisors, a registered adviser under the Investment Advisers Act of 1940, as amended, is the sole managing member of Capital. Pursuant to those relationships, Capital and Advisors have discretionary investment management authority with respect to the assets of OPI III. Such authority includes the power to vote and otherwise dispose of securities held by OPI III.
(3)	Isaly, a natural person, is the managing member of, and holder of a controlling interest, in Advisors. In such capacity, Isaly may also be deemed to have investment and voting power over the Shares held by OPI III. As a result, each of Capital, Advisors and Isaly may be deemed to have beneficial ownership of the Shares held by OPI III.
(4)	This report on Form 4 is jointly filed by Capital, Advisors and Isaly. Each of the reporting persons disclaims beneficial ownership of the Shares reported herein for purposes of Rule 16a-1(a) under the Securities Exchange Act of 1934, as amended (the "Exchange Act"), except to the extent of its or his pecuniary interest therein, if any. The reporting persons have designated a representative, currently Carl L. Gordon, a member of Advisors, to serve on the Issuer's board of directors. This report shall not be deemed an admission that the reporting persons are beneficial owners for the purpose of Section 16 of the Exchange Act, or for any other purpose.
(5)	These Shares are directly owned by OrbiMed Associates III, LP ("Associates") and may be deemed to be indirectly beneficially owned by Advisors and Isaly. Advisors is the sole general partner of Associates. Pursuant to that relationship, Advisors has discretionary investment management authority with respect to the assets of Associates. Such authority includes the power to vote and otherwise dispose of securities held by Associates. Isaly, in his capacity as the managing member of, and holder of a controlling interest, in Advisors, may also be deemed to have voting and investment power over the Shares held by Associates. As a result, each of Advisors and Isaly may be deemed to have beneficial ownership of the Shares held by Associates.
(6)	The price reported in Column 4 is a weighted average price. These Shares were sold in multiple transactions at prices ranging from $15.70 to $16.69, inclusive. The reporting persons undertake to provide to the Issuer, any security holder of the Issuer or the Staff of the Securities and Exchange Commission, upon request, full information regarding the number of Shares sold at each separate price within the range set forth in this footnote.
(7)	The price reported in Column 4 is a weighted average price. These Shares were sold in multiple transactions at prices ranging from $16.70 to $17.08, inclusive. The reporting persons undertake to provide to the Issuer, any security holder of the Issuer or the Staff of the Securities and Exchange Commission, upon request, full information regarding the number of Shares sold at each separate price within the range set forth in this footnote.

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