FEDERATED MDT SERIES Federated Investors Funds 5800 Corporate Drive Pittsburgh, Pennsylvania 15237-7000 August 11, 2006 EDGAR Operations Branch Securities and Exchange Commission Division of Investment Management 450 Fifth Street, Northwest Washington, DC 20549 RE: FEDERATED MDT SERIES (the "Trust") Federated MDT All Cap Core Fund Federated MDT Tax Aware/All Cap Core Fund Federated MDT Large Cap Growth Fund Federated MDT Mid Cap Growth Fund Federated MDT Balanced Fund Federated MDT Small Cap Core Fund Federated MDT Small Cap Growth Fund Federated MDT Small Cap Value Fund (collectively, the "Funds") 1933 Act File No. 333- 1940 Act File No. 811-21904 Dear Sir or Madam: On behalf of the Trust, we hereby request, pursuant to Rule 477 of the Securities Act of 1933, as amended (the "Securities Act"), that the N14 filing including all exhibits thereto (File No. 333-136520 and ACC. No. 0001318148-06-0011070), as originally filed by the Trust with the Securities and Exchange Commission on August 11, 2006 be withdrawn effective immediately. The filing was made inadvertently by the Trust due to an administrative error and accordingly, the Trust is seeking immediate withdrawal of the N14 filing. Please contact Cole Dolinger at 412-288-2292 with any questions regarding this filing. Respectfully, /s/ Todd P. Zerega Todd P. Zerega Assistant Secretary Enclosures