July 17, 2019

Jack A. Khattar
President, Secretary and Chief Executive Officer
Supernus Pharmaceuticals, Inc.
1550 East Gude Drive
Rockville, Maryland 20850

       Re: Supernus Pharmaceuticals, Inc.
           Form 10-Q for the Quarterly Period Ended March 31, 2019
           Filed May 10, 2019
           File No. 001-35518

Dear Mr. Khattar:

      We have limited our review of your filing to those issues we have
addressed in our
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 these comments within ten business days by providing
the requested
information or advise us as soon as possible when you will respond. If you do
not believe our
comments apply to your facts and circumstances, please tell us why in your
response.

       After reviewing your response to these comments, we may have additional
comments.

Form 10-Q for the Quarterly Period Ended March 31, 2019

Item 2 Management's Discussion and Analysis of Financial Condition and Results
of Operations
Results of Operations
Comparison of the three month periods ended March 31, 2019 and 2018
Net Product Sales, page 28

1.    Regarding sales discounts, please tell us why the provision for sales in
the current year as
      a percentage of gross product sales during the quarter and the allowance
as a percentage of
      gross accounts receivable as of the end of the quarter both decreased in
2019 as compared
      to the 2018.
2.    Regarding the accrued liability for rebates, please tell us why it was
$18.9 million higher
      at December 31, 2018 than at March 31, 2019.
3.    Please consider whether revised disclosure is necessary in response to
the above
      comments and, if so, provide us proposed disclosure to be included in
your June 30, 2019
 Jack A. Khattar
Supernus Pharmaceuticals, Inc.
July 17, 2019
Page 2
         Form 10-Q.
       In closing, 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.

       You may contact Andi Carpenter at 202-551-3645 or Jim Rosenberg at
202-551-3679
with any questions.



FirstName LastNameJack A. Khattar                         Sincerely,
Comapany NameSupernus Pharmaceuticals, Inc.
                                                          Division of
Corporation Finance
July 17, 2019 Page 2                                      Office of Healthcare
& Insurance
FirstName LastName