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                            May 19, 2021

       Robert Spignesi
       President and Chief Executive Officer
       Rapid Micro Biosystems, Inc.
       1001 Pawtucket Boulevard West, Suite 280
       Lowell, MA 01854

                                                        Re: Rapid Micro
Biosystems, Inc.
                                                            Amendment No. 1 to
                                                            Draft Registration
Statement on Form S-1
                                                            Submitted May 7,
2021
                                                            CIK No. 0001380106

       Dear Mr. Spignesi:

             We have reviewed your amended 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
       comments.

       Amendment No. 1 to Draft Registration Statement on Form S-1

       Our Market, page 6

   1.                                                   We note the disclosure
added in response to our prior comment 4. Please provide details
                                                        regarding Health
Advances LLC and the company's relationship thereto, including
                                                        whether or not any
studies were commissioned in connection with the registration
                                                        statement. If so,
please consider the application of Securities Act Rule 436.
       Management's Discussion and Analysis, page 62
       Critical accounting policies and significant judgments and estimates,
page 79

   2.                                                   We have read your
response to comment 8 in our letter dated April 19, 2021. Please
 Robert Spignesi
Rapid Micro Biosystems, Inc.
May 19, 2021
Page 2
       further clarify how, if the System will accept only your Consumables to
complete ongoing
       testing and orders for such Consumables are typically placed separately
from that of the
       System, your customers benefit from the use of the System "[u]pon
purchase". Please
       clarify if orders for Consumables are typically placed only after the
completion of
       validation services. Finally, in the cases when a customer purchases the
System and
       Consumables at the same time, confirm, if true, whether you allocate the
contract   s
       transaction price to each performance obligation on a relative
standalone selling price
       basis, as you have indicated you do when the LIMS connection software is
purchased as
       part of the initial System sale.
Business
Intellectual property, page 109

3.     We note your response to prior comment 10. Please further revise your
disclosure to
       include:
           the type of patent protection for the patents issued or applied for
(i.e., composition of
            matter, use or process);
           the expiration year of each patent or pending patent application on
an individual
            basis;
           the identity of the European countries in which you have issued
patents with respect
            to your (i) your technology related to rapid detection of
replicating cells and (ii) your
            cassette for sterility testing.
       In this regard, it may be useful to provide tabular disclosure.
License Agreement, page 109

4.     We note your response to our prior comment 9. Please provide more
specificity around the
       fixed dollar royalty range. As drafted, a range of "the low to mid
thousands of dollars"
       may be widely interpreted and could mean $1,000 to $5,000 or $1,000 to
$50,000. Please
       revise.
       You may contact Jenn Do at 202-551-3743 or Daniel Gordon at 202-551-3486
if you
have questions regarding comments on the financial statements and related
matters. Please
contact David Gessert at 202-551-2326 or Laura Crotty at 202-551-7614 with any
other
questions.



                                                              Sincerely,
FirstName LastNameRobert Spignesi
                                                              Division of
Corporation Finance
Comapany NameRapid Micro Biosystems, Inc.
                                                              Office of Life
Sciences
May 19, 2021 Page 2
cc:       Wesley C. Holmes
FirstName LastName