United States securities and exchange commission logo June 24, 2020 Oliver Schacht, Ph.D. Chief Executive Officer OpGen, Inc. 708 Quince Orchard Road, Suite 205 Gaithersburg, MD 20878 Re: OpGen, Inc. Registration Statement on Form S-3 Filed June 17, 2020 File No. 333-239240 Dear Dr. Schacht: This is to advise you that we have not reviewed and will not review your registration statement. Please refer to Rules 460 and 461 regarding requests for acceleration. We remind you that the company and its management are responsible for the accuracy and adequacy of their disclosures, notwithstanding any review, comments, action or absence of action by the staff. Please contact Ada D. Sarmento at 202-551-3798 with any questions. Sincerely, Division of Corporation Finance Office of Life Sciences cc: Peter Jaslow, Esq.