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 * FMR LLC   2. Issuer Name and Ticker or Trading Symbol REGENXBIO Inc. [RGNX] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) _____ Director __X__ 10% Owner _____ Officer (give title below) __X__ Other (specify below) See Remark 1 (Last) (First) (Middle) 245 SUMMER STREET 3. Date of Earliest Transaction (Month/Day/Year) 05/06/2016 (Street) BOSTON, MA 02210 4. If Amendment, Date 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 (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 Common Stock 05/06/2016   S   977 D $ 9.91 (2) 695,142 I See footnote (1) Common Stock 05/06/2016   S   900 D $ 10.03 (3) 694,242 I See footnote (1) Common Stock 05/06/2016   S   600 D $ 9.9 (4) 693,642 I See footnote (1) Common Stock 05/06/2016   S   600 D $ 9.98 (5) 693,042 I See footnote (1) Common Stock 05/06/2016   S   562 D $ 9.95 (6) 692,480 I See footnote (1) Common Stock 05/06/2016   S   500 D $ 9.99 (7) 691,980 I See footnote (1) Common Stock 05/06/2016   S   300 D $ 9.9 691,680 I See footnote (1) Common Stock 05/06/2016   S   200 D $ 9.89 (8) 691,480 I See footnote (1) Common Stock 05/06/2016   S   100 D $ 9.94 691,380 I See footnote (1) Common Stock 05/06/2016   S   100 D $ 10.05 691,280 I See footnote (1) Common Stock 05/09/2016   S   4,431 D $ 9.94 (9) 686,849 I See footnote (1) Common Stock 05/09/2016   S   400 D $ 9.89 (10) 686,449 I See footnote (1) Common Stock 05/09/2016   S   300 D $ 9.94 (11) 686,149 I See footnote (1) Common Stock 05/09/2016   S   200 D $ 9.88 (12) 685,949 I See footnote (1) Common Stock 05/09/2016   S   200 D $ 9.89 685,749 I See footnote (1) Common Stock 05/09/2016   S   200 D $ 9.9 685,549 I See footnote (1)

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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
FMR LLC 245 SUMMER STREET BOSTON, MA 02210		X		See Remark 1

Signatures

Daniel T. Gallagher, Duly authorized under Powers of Attorney, by and on behalf of FMR LLC and its direct and indirect subsidiaries and Abigail P. Johnson		05/10/2016
**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)	By F-Prime Capital Partners Healthcare Fund III LP, Impresa Fund III Limited Partnership and F-Prime Inc. The general partner of F-Prime Capital Partners Healthcare Fund III LP is F-Prime Capital Partners Healthcare Advisors Fund III LP (FPCPHA). FPCPHA and Impresa Fund III Limited Partnership are each solely managed by Impresa Management LLC, their general partner and investment manager. Impresa Management LLC is owned, directly or indirectly, by various shareholders and employees of FMR LLC, including certain members of the Johnson family. F-Prime Inc. is a wholly-owned subsidiary of FMR LLC.
(2)	The price reported for this transaction is the weighted average price of multiple trades at prices ranging from $9.83 to $10.06. FMR LLC hereby undertakes to provide upon request by the Commission staff, the issuer, or a security holder of the issuer full information regarding the number of shares and prices at which the transaction was effected.
(3)	The price reported for this transaction is the weighted average price of multiple trades at prices ranging from $9.93 to $10.16. FMR LLC hereby undertakes to provide upon request by the Commission staff, the issuer, or a security holder of the issuer full information regarding the number of shares and prices at which the transaction was effected.
(4)	The price reported for this transaction is the weighted average price of multiple trades at prices ranging from $9.84 to $10.11. FMR LLC hereby undertakes to provide upon request by the Commission staff, the issuer, or a security holder of the issuer full information regarding the number of shares and prices at which the transaction was effected.
(5)	The price reported for this transaction is the weighted average price of multiple trades at prices ranging from $9.90 to $10.06. FMR LLC hereby undertakes to provide upon request by the Commission staff, the issuer, or a security holder of the issuer full information regarding the number of shares and prices at which the transaction was effected.
(6)	The price reported for this transaction is the weighted average price of multiple trades at prices ranging from $9.85 to $10.07. FMR LLC hereby undertakes to provide upon request by the Commission staff, the issuer, or a security holder of the issuer full information regarding the number of shares and prices at which the transaction was effected.
(7)	The price reported for this transaction is the weighted average price of multiple trades at prices ranging from $9.83 to $10.10. FMR LLC hereby undertakes to provide upon request by the Commission staff, the issuer, or a security holder of the issuer full information regarding the number of shares and prices at which the transaction was effected.
(8)	The price reported for this transaction is the weighted average price of multiple trades at prices ranging from $9.89 to $9.90. FMR LLC hereby undertakes to provide upon request by the Commission staff, the issuer, or a security holder of the issuer full information regarding the number of shares and prices at which the transaction was effected.
(9)	The price reported for this transaction is the weighted average price of multiple trades at prices ranging from $9.82 to $10.19. FMR LLC hereby undertakes to provide upon request by the Commission staff, the issuer, or a security holder of the issuer full information regarding the number of shares and prices at which the transaction was effected.
(10)	The price reported for this transaction is the weighted average price of multiple trades at prices ranging from $9.89 to $9.90. FMR LLC hereby undertakes to provide upon request by the Commission staff, the issuer, or a security holder of the issuer full information regarding the number of shares and prices at which the transaction was effected.
(11)	The price reported for this transaction is the weighted average price of multiple trades at prices ranging from $9.88 to $10.02. FMR LLC hereby undertakes to provide upon request by the Commission staff, the issuer, or a security holder of the issuer full information regarding the number of shares and prices at which the transaction was effected.
(12)	The price reported for this transaction is the weighted average price of multiple trades at prices ranging from $9.87 to $9.89. FMR LLC hereby undertakes to provide upon request by the Commission staff, the issuer, or a security holder of the issuer full information regarding the number of shares and prices at which the transaction was effected.
Remarks: Remark 1: Abigail P. Johnson is a Director, the Vice Chairman, the Chief Executive Officer and the President of FMR LLC. Members of the Johnson family, including Abigail P. Johnson, are the predominant owners, directly or through trusts, of Series B voting common shares of FMR LLC, representing 49% of the voting power of FMR LLC. The Johnson family group and all other Series B shareholders have entered into a shareholders' voting agreement under which all Series B voting common shares will be voted in accordance with the majority vote of Series B voting common shares. Accordingly, through their ownership of voting common shares and the execution of the shareholders' voting agreement, members of the Johnson family may be deemed, under the Investment Company Act of 1940, to form a controlling group with respect to FMR LLC. The address of Abigail P. Johnson is c/o FMR LLC, 245 Summer Street, Boston, MA 02110. Remark 2: FMR Co., Inc. (FMRC), an indirect wholly-owned subsidiary of FMR LLC and an investment adviser registered under the Investment Advisers Act of 1940,  and Fidelity Institutional Asset Management Trust Company (FIAMTC), an indirect wholly-owned subsidiary of FMR LLC and a bank as defined in Section 3(a)(6) of the Securities Exchange Act of 1934, are the beneficial owners of Common Stock of REGENXBIO Inc. as a result of acting as investment adviser to various client funds and accounts. FMR LLC and Abigail P. Johnson have no pecuniary interest in the Common Stock beneficially owned by FMRC and FIAMTC. Remark 3: The filing of this statement shall not be deemed to be an admission that, for purposes of Section 16 of the Securities Exchange Act of 1934 or otherwise, the undersigned are the beneficial owners of any securities reported herein.

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