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                            SECTION 906 CERTIFICATION

                Certification Pursuant to 18 U.S.C. Section 1350,
                             As Adopted Pursuant to

                  Section 906 of the Sarbanes-Oxley Act of 2002

Morgan Stanley Mid-Cap Value Fund

     In connection with the Report on Form N-CSR (the "Report") of the
above-named issuer for the period ended August 31, 2006 that is accompanied by
this certification, the undersigned hereby certifies that:

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

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

Date: October 19, 2006                  /s/ Ronald E. Robison
                                        ----------------------------------------
                                        Ronald E. Robison
                                        Principal Executive Officer

A signed original of this written statement required by Section 906 has been
provided to Morgan Stanley Mid-Cap Value Fund and will be retained by Morgan
Stanley Mid-Cap Value Fund and furnished to the Securities and Exchange
Commission or its staff upon request.

<Page>

                            SECTION 906 CERTIFICATION

                Certification Pursuant to 18 U.S.C. Section 1350,
                             As Adopted Pursuant to

                  Section 906 of the Sarbanes-Oxley Act of 2002

Morgan Stanley Mid-Cap Value Fund

     In connection with the Report on Form N-CSR (the "Report") of the
above-named issuer for the period ended August 31, 2006 that is accompanied by
this certification, the undersigned hereby certifies that:

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

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

Date: October 19, 2006                  /s/ Francis Smith
                                        ----------------------------------------
                                        Francis Smith
                                        Principal Financial Officer

A signed original of this written statement required by Section 906 has been
provided to Morgan Stanley Mid-Cap Value Fund and will be retained by Morgan
Stanley Mid-Cap Value Fund and furnished to the Securities and Exchange
Commission or its staff upon request.