Exhibit (b)

                         CDC Nvest Cash Management Trust
                            Section 906 Certification

     In connection with the report on Form N-CSR for the period ended June 30,
2004 for the Registrant (the "Report"), the undersigned each hereby certifies to
the best of his knowledge, pursuant to section 906 of the Sarbanes-Oxley Act of
2002, that:

     1. the Report complies with the requirements of Section 13(a) or 15(d) of
the Securities and Exchange Act of 1934, as applicable; and

     2. the information contained in the Report fairly presents, in all material
respects, the financial condition and results of operations of the Registrant.


By:                                              By:
President & Chief Executive Officer              Treasurer
CDC Nvest Cash Management Trust                  CDC Nvest Cash Management Trust

/s/ John T. Hailer                               /s/ Nicholas H. Palmerino
- -----------------------------------              -------------------------------
John T. Hailer                                   Nicholas H. Palmerino

Date: August 20, 2004                            Date: August 20, 2004

A signed original of this written statement required by Section 906, or other
document authenticating, acknowledging, or otherwise adopting the signature that
appears in typed form within the electronic version of this written statement
required by Section 906, has been provided to the CDC Nvest Cash Management
Trust, and will be retained by the CDC Nvest Cash Management Trust and furnished
to the Securities and Exchange Commission (the "Commission") or its staff upon
request.