Certification of No Change in Definitive Materials. (497j)

111 Huntington Avenue, Boston, Massachusetts  02199

[phone]

March 5, 2013

VIA EDGAR

United States Securities and Exchange Commission

100 F Street, N.E.

Washington, DC  20549

Re:

MFS ® Series Trust IX (the “Trust”) (File Nos. 2-50409 and 811-2464) on Behalf of MFS ® Inflation-Adjusted Bond Fund (the “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 Prospectus and Statement of Additional Information for the Trust do not differ from those contained in Post-Effective Amendment No. 82 (the “Amendment”) to the Trust’s Registration Statement on Form N-1A.  The Amendment was filed electronically on February 27, 2013.

Please call the undersigned at [phone] or Nickolas Connery at [phone] with any questions you may have.

Very truly yours,

 

 

SUSAN A. PEREIRA

Susan A. Pereira

Vice President and Senior Counsel

SAP/bjn

enclosure