MFS SERIES TRUST IX /MA/, 497J, 2000-09-05

MFS SERIES TRUST IX /MA/
497J, 2000-09-05

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                                        September 5, 2000



VIA EDGAR
Securities and Exchange Commission
Judiciary Plaza
450 Fifth Street, NW
Washington, DC  20549

         Re:   MFS(R)Series  Trust  IX (the  "Trust")  (File  Nos.  2-50409  and
               811-2464) on Behalf of MFS(R)Bond  Fund,  MFS(R)Limited  Maturity
               Fund,  MFS(R)Municipal Limited Maturity Fund,  MFS(R)Intermediate
               Investment Grade Bond Fund and MFS(R) Research Bond Fund

Ladies and Gentlemen:

         Pursuant to Rule 497(j) under the  Securities  Act of 1933, as amended,
please  accept  this  letter on behalf  of the Trust as  certification  that the
Prospectuses  and  Statements  of  Additional  Information  for the Trust do not
differ from those  contained in  Post-Effective  Amendment No. 40 to the Trust's
Registration  Statement on Form N-1A. The Amendment was filed  electronically on
August 28, 2000.

         Please call the  undersigned or Shauna Fahey at (617) 954-5000 or (800)
343-2829 with any questions you may have.

                                        Very truly yours,




                                        HEATHER R. GIROLAMO
                                        Heather R. Girolamo
                                        Associate Counsel

HRG/bjn