January 10, 2020

Evan Jones
Chief Executive Officer
OpGen, Inc.
708 Quince Orchard Road, Suite 205
Gaithersburg, MD 20878

       Re: OpGen, Inc.
           Amendment No. 1 to Registration Statement on Form S-4
           Filed December 20, 2019
           File No. 333-234657

Dear Mr. Jones:

      We have reviewed your amended 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 amending your registration statement
and providing the
requested information. 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 any amendment to your registration statement and the
information you
provide in response to these comments, we may have additional comments. Unless
we note
otherwise, our references to prior comments are to comments in our December 12,
2019 letter.

Amendment No. 1 to Registration Statement on Form S-4 filed December 20, 2019

Curetis' Business
Curetis' Partnering and Collaboration Agreements, page 139

1.     We note that on September 16, 2019, Ares Genetics entered into a
multi-phase partnership
       with an undisclosed leading global in vitro diagnostics corporation.
Please identify the
       undisclosed party and to the extent material, disclose the up-front
option fee. In the
       alternative, tell us why you believe you are not required to identify
the party and the up-
       front option fee.
 Evan Jones
FirstName LastNameEvan Jones
OpGen, Inc.
Comapany NameOpGen, Inc.
January 10, 2020
Page 2
January 10, 2020 Page 2
FirstName LastName
Acquisition Agreements, page 143

2.       We note your response to prior comment 14. For your GEAR asset
acquisition, please
         expand your disclosure to include the aggregate future potential
milestone payments.
Patents, page 160

3.       We note that the opposition proceedings against the European Patent EP
2 571 976 B1
         was lost by Curetis GmbH and the corresponding patent was revoked.
Please disclose
         whether the loss of this patent would have a material negative impact
on the conduct of
         your business and identify the applicable products and/or technologies
that would be
         impacted.
Unaudited Interim Condensed Combined Statement of Operations and Other
Comprehensive
Loss for Curetis Business, page F-93

4.       While you have provided updated interim information as of September
30, 2019 for
         Curetis Business in your pro forma financial statements here, we note
that you have not
         provided the complete interim financial statements including footnotes
as of September
         30, 2019 for Curetis Business. Tell us how you determined that it was
appropriate not to
         update the Curetis Business interim financial statements to be
consistent with the
         information provided in your pro forma presentation. Identify the
guidance you
         considered in reaching your conclusion.
       You may contact Franklin Wyman at 202-551-3660 or Kevin Vaughn at
202-551-3494 if
you have questions regarding comments on the financial statements and related
matters. Please
contact Jeffrey Gabor at 202-551-2544 or Mary Beth Breslin at 202-551-3625 with
any other
questions.



                                                              Sincerely,

                                                              Division of
Corporation Finance
                                                              Office of Life
Sciences
cc:      Mary J. Mullany, Esq.