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                     June 10, 2024

       Howard Horn
       Executive Vice President
       Ultragenyx Pharmaceutical Inc.
       60 Leveroni Court
       Novato, CA 94949

                                                        Re: Ultragenyx 
Pharmaceutical Inc.
                                                            Form 10-K for 
Fiscal Year Ended December 31, 2023
                                                            File No. 1-36276

       Dear Howard Horn:

              We have completed our review of your filing. 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.



                                                                                
                     Sincerely,

                                                                                
                     Division of Corporation Finance
                                                                                
                     Office of Life Sciences