Initial Statement of Beneficial Ownership (3)

FORM 3	UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 INITIAL STATEMENT OF BENEFICIAL OWNERSHIP OF SECURITIES	OMB APPROVAL OMB Number: 3235-0104 Estimated average burden hours per response... 0.5
	Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934 or Section 30(h) of the Investment Company Act of 1940

1. Name and Address of Reporting Person ^*

Tsai Larry

2. Date of Event Requiring Statement (MM/DD/YYYY) 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 /

(Street)

WATERTOWN, MA 02472

(City) (State) (Zip)

5. If Amendment, Date Original Filed (MM/DD/YYYY)

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	28166	D

*Table II - Derivative Securities Beneficially Owned ( e.g.* , puts, calls, warrants, options, convertible securities)**
1. Title of Derivate Security (Instr. 4)	2. Date Exercisable and Expiration Date (MM/DD/YYYY)		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)
1. Title of Derivate Security (Instr. 4)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares	4. Conversion or Exercise Price of Derivative Security		6. Nature of Indirect Beneficial Ownership (Instr. 5)
Employee Stock Option (Right to Buy)	⁽¹⁾	3/31/2024	Common Stock	60000	$11.30	D
Employee Stock Option (Right to Buy)	⁽²⁾	1/6/2025	Common Stock	29000	$39.94	D
Employee Stock Option (Right to Buy)	⁽³⁾	1/5/2026	Common Stock	20000	$8.47	D
Employee Stock Option (Right to Buy)	⁽⁴⁾	1/29/2027	Common Stock	50000	$3.69	D
Restricted Stock Units	⁽⁵⁾	⁽⁵⁾	Common Stock	8000	⁽⁶⁾	D

Explanation of Responses:
(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.

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

Signatures
/s/Maria Stahl as Attorney-in-Fact for Larry Tsai		1/4/2018
^** 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).
Note:	File three copies of this Form, one of which must be manually signed. If space is insufficient, see Instruction 6 for procedure.
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.