Mail Stop 3030
                                                                 January 4,

     Manoussos Perros, Ph.D.
     Chief Executive Officer
     Entasis Therapeutics Limited
     35 Gatehouse Drive
     Waltham, MA 02451

            Re:     Entasis Therapeutics Limited
                    Draft Registration Statement on Form S-1
                    Submitted December 8, 2017
                    CIK No. 0001724344

     Dear Dr. Perros:

            We have reviewed your draft registration statement and have the
following comments. In
     some of our comments, we may ask you to provide us with information so we
may better
     understand your disclosure.

            Please respond to this letter by providing the requested
information and either submitting
     an amended draft registration statement or publicly filing your
registration statement on
     EDGAR. If you do not believe our comments apply to your facts and
circumstances or do not
     believe an amendment is appropriate, please tell us why in your response.

           After reviewing the information you provide in response to these
comments and your
     amended draft registration statement or filed registration statement, we
may have additional

     Overview, page 1

     1.     We note the market data disclosed in your submission. Please revise
to clarify how such
            data relates to the actual market that may be addressed by each of
your products for the
            regulatory indications you intend to pursue.

     Implications of the Being an Emerging Growth Company, page 8

     2.     Supplementally provide us with copies of all written
communications, as defined in
            Rule 405 under the Securities Act, that you, or anyone authorized
to do so on your behalf,
            present to potential investors in reliance on Section 5(d) of the
Securities Act, whether or
            not they retain copies of the communication.
 Manoussos Perros, Ph.D.
Entasis Therapeutics Limited
January 4, 2018
Page 2

Use of Proceeds, page 67

3.     If material, indicate your estimated use of net proceeds for development
of your
       zoliflodacin candidate.

Corporate Reorganization, page 70

4.     The first sentence of the first paragraph states that Entasis
Therapeutics Limited will be
       the issuer in this offering. Later in that paragraph, you indicate that
Entasis Therapeutics
       plc will issue ordinary shares in this offering. Please revise to
clarify who will be the
       issuer of ordinary shares in this offering.

5.     Revise to describe briefly the purpose of the transactions referenced in
this section.

Dilution, page 73

6.     Disclose how the numbers and percentages in the table on page 74 would
       assuming the exercise of all outstanding options.

Funding Arrangements, page 78

7.     Please revise to clarify what are "qualified research expenditures"
under the disclosed
       arrangements. Include in your revisions any material conditions you must
satisfy in order
       to receive funds under those arrangements. We note, for example, the
       milestones" referenced on pages 67 and 114.

Business, page 90

8.     Indicate how your products target "clinically validated mechanisms" in
order to address
       antibiotic resistance. Clarify the nature of such clinical validation
including the nature of
       the parties that validated the mechanisms and the basis for your belief
that those
       mechanisms were validated.

9.     We note from your disclosure that some of your products appear to be
genus or species
       specific. Disclose if pathogen identification and resistance profiling
could be required
       before your product candidates, if approved, would be used and if the
costs and timing
       associated with such tests, if any, would be a competitive disadvantage
for your products
       as compared to the use of existing broad-spectrum antibiotics. Include
risk factor
       disclosure as appropriate.
 Manoussos Perros, Ph.D.
Entasis Therapeutics Limited
January 4, 2018
Page 3

Zoliflodacin for the treatment of uncomplicated gonorrhea, page 93

10.    We note your disclosure in the last sentence of the first paragraph of
this section. Clarify,
       if known, the resistance rates for current treatments. Please also
clarify what you mean
       by "uncomplicated gonorrhea."

Our Scientific Platform, page 94

11.    Include additional disclosure so that investors can better understand
the nature of your
       platform. Indicate whether the platform is protected by any intellectual
property rights
       and whether AstraZeneca retained any rights to the platform, future
improvements to the
       platform or product candidates developed with the platform. Clarify how
the platform
       gives you a competitive advantage, if any.

Business Transfer and Subscription Agreement with AstraZeneca, page 114

12.    Please disclose the cumulative net sales milestones referenced here and
the amount of the
       royalties applicable to worldwide sales of zoliflodacin. Also clarify
whether worldwide
       sales of zoliflodacin applies only to sales by you in the "major
markets" referenced on
       page 115 or whether it also includes the low-income and middle-income
countries where
       DNDi may commercialize the product.

Collaboration Agreement with DNDi, page 115

13.    Please clarify how ownership of intellectual property will be determined
under this
       agreement. Considering your disclosure that DNDi is funding clinical
trials, it is unclear
       how you may develop intellectual property under the collaboration


14.    Please include the signature of the registrant's authorized
representative in the United
 Manoussos Perros, Ph.D.
Entasis Therapeutics Limited
January 4, 2018
Page 4

        You may contact Julie Sherman at (202) 551-3640 or Gary Todd, Senior
Accountant, at
(202) 551-3605 if you have questions regarding comments on the financial
statements and
related matters. Please contact Geoff Kruczek at (202) 551-3641 or Tim
Buchmiller, Senior
Attorney, at (202) 551-3635 with any other questions.


                                                         /s/ Tim Buchmiller for

                                                         Amanda Ravitz
                                                         Assistant Director
                                                         Office of Electronics
and Machinery

cc:    Jaime Chase, Esq.
       Cooley LLP