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

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(Print or Type Responses)

1. Name and Address of Reporting Person *   Tsai Larry 2. Date of Event Requiring Statement (Month/Day/Year) 12/29/2017 3. Issuer Name and Ticker or Trading Symbol TETRAPHASE PHARMACEUTICALS INC [TTPH] (Last) (First) (Middle) C/OTETRAPHASE PHARMACEUTICALS, 480 ARSENAL WAY 4. Relationship of Reporting Person(s) to Issuer (Check all applicable) _____ Director _____ 10% Owner __X__ Officer (give title below) _____ Other (specify below) Chief Medical Officer 5. If Amendment, Date Original Filed(Month/Day/Year) (Street) WATERTOWN, MA 02472 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 28,166 D Â

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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
Employee Stock Option (Right to Buy)	  (1)	03/31/2024	Common Stock	60,000	$ 11.3	D	Â
Employee Stock Option (Right to Buy)	  (2)	01/06/2025	Common Stock	29,000	$ 39.94	D	Â
Employee Stock Option (Right to Buy)	  (3)	01/05/2026	Common Stock	20,000	$ 8.47	D	Â
Employee Stock Option (Right to Buy)	  (4)	01/29/2027	Common Stock	50,000	$ 3.69	D	Â
Restricted Stock Units	  (5)	  (5)	Common Stock	8,000	$ (6)	D	Â

Reporting Owners

Reporting Owner Name / Address	Relationships
	Director	10% Owner	Officer	Other
Tsai Larry C/OTETRAPHASE PHARMACEUTICALS 480 ARSENAL WAY WATERTOWN, MA 02472	Â	Â	  Chief Medical Officer	Â

Signatures

/s/Maria Stahl as Attorney-in-Fact for Larry Tsai		01/04/2018
**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)	This option vests over four years. Twenty-five percent (25%) of the shares vested on April 1, 2015 and 6.25% of the shares will vest at the end of each successive three-month period thereafter.
(2)	Vests as to 6.25% of the shares on 4/7/2015 and further vests as to an additional 6.25% of the original grant at the end of each successive three-month period thereafter until 1/7/2019.
(3)	Vests as to 6.25% of the shares on 4/6/2016 and further vests as to an additional 6.25% of the original grant at the end of each successive three-month period thereafter until 1/6/2020.
(4)	Vests as to 6.25% of the shares on 4/30/2017 and further vests as to an additional 6.25% of the original grant at the end of each successive three-month period thereafter until 1/30/2021.
(5)	The restricted stock units vest in three equal installments on each of January 6, 2017, January 6, 2018 and January 6, 2019.
(6)	Each restricted stock unit represents a contingent right to receive one share of common stock of Tetraphase Pharmaceuticals, Inc. for no consideration.

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