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                                                                      EXHIBIT B1

                  CERTIFICATION OF PRINCIPAL EXECUTIVE OFFICER

                                 CERTIFICATIONS

I, Ronald E. Robison, certify that:

          1. I have reviewed this report on Form N-CSR of Morgan Stanley Select
Dimensions Investment Series;

          2. Based on my knowledge, this report does not contain any untrue
             statement of a material fact or omit to state a material fact
             necessary to make the statements made, in light of the
             circumstances under which such statements were made, not misleading
             with respect to the period covered by this report;

          3. Based on my knowledge, the financial statements, and other
             financial information included in this report, fairly present in
             all material respects the financial condition, results of
             operations, changes in net assets, and cash flows (if the financial
             statements are required to include a statement of cash flows) of
             the registrant as of, and for, the periods presented in this
             report;

          4. The registrant's other certifying officers and I are responsible
             for establishing and maintaining disclosure controls and procedures
             (as defined in Rule 30a-2(c) under the Investment Company Act of
             1940) for the registrant and have:

          a) designed such disclosure controls and procedures to ensure that
             material information relating to the registrant, including its
             consolidated subsidiaries, is made known to us by others within
             those entities, particularly during the period in which this report
             is being prepared;

          b) evaluated the effectiveness of the registrant's disclosure controls
             and procedures as of a date within 90 days prior to the filing date
             of this report (the "Evaluation Date"); and

          c) presented in this report our conclusions about the effectiveness of
             the disclosure controls and procedures based on our evaluation as
             of the Evaluation Date;

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          5. The registrant's other certifying officers and I have disclosed,
             based on our most recent evaluation, to the registrant's auditors
             and the audit committee of the registrant's board of directors (or
             persons performing the equivalent functions):

          a) all significant deficiencies in the design or operation of internal
             controls which could adversely affect the registrant's ability to
             record, process, summarize, and report financial data and have
             identified for the registrant's auditors any material weaknesses in
             internal controls; and

          b) any fraud, whether or not material, that involves management or
             other employees who have a significant role in the registrant's
             internal controls; and

          6. The registrant's other certifying officers and I have indicated in
             this report whether or not there were significant changes in
             internal controls or in other factors that could significantly
             affect internal controls subsequent to the date of our most recent
             evaluation, including any corrective actions with regard to
             significant deficiencies and material weaknesses.

          Date: August 19, 2003


                                               Ronald E. Robison

                                               Principal Executive Officer

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                                                                      EXHIBIT B2

                  CERTIFICATION OF PRINCIPAL FINANCIAL OFFICER

                                 CERTIFICATIONS

I, Francis Smith, certify that:

          1. I have reviewed this report on Form N-CSR of Morgan Stanley Select
Dimensions Investment Series;

          2. Based on my knowledge, this report does not contain any untrue
             statement of a material fact or omit to state a material fact
             necessary to make the statements made, in light of the
             circumstances under which such statements were made, not misleading
             with respect to the period covered by this report;

          3. Based on my knowledge, the financial statements, and other
             financial information included in this report, fairly present in
             all material respects the financial condition, results of
             operations, changes in net assets, and cash flows (if the financial
             statements are required to include a statement of cash flows) of
             the registrant as of, and for, the periods presented in this
             report;

          4. The registrant's other certifying officers and I are responsible
             for establishing and maintaining disclosure controls and procedures
             (as defined in Rule 30a-2(c) under the Investment Company Act of
             1940) for the registrant and have:

          (i)   designed such disclosure controls and procedures to ensure that
                material information relating to the registrant, including its
                consolidated subsidiaries, is made known to us by others within
                those entities, particularly during the period in which this
                report is being prepared;

          (ii)  evaluated the effectiveness of the registrant's disclosure
                controls and procedures as of a date within 90 days prior to the
                filing date of this report (the "Evaluation Date"); and

          (iii) presented in this report our conclusions about the effectiveness
                of the disclosure controls and procedures based on our
                evaluation as of the Evaluation Date;

          5. The registrant's other certifying officers and I have disclosed,
             based on our most recent evaluation, to the registrant's auditors
             and the audit committee of the registrant's board of directors (or
             persons performing the equivalent functions):

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          a) all significant deficiencies in the design or operation of internal
             controls which could adversely affect the registrant's ability to
             record, process, summarize, and report financial data and have
             identified for the registrant's auditors any material weaknesses in
             internal controls; and

          b) any fraud, whether or not material, that involves management or
             other employees who have a significant role in the registrant's
             internal controls; and

          6. The registrant's other certifying officers and I have indicated in
             this report whether or not there were significant changes in
             internal controls or in other factors that could significantly
             affect internal controls subsequent to the date of our most recent
             evaluation, including any corrective actions with regard to
             significant deficiencies and material weaknesses.

          Date: August 19, 2003


                                               Francis Smith

                                               Principal Financial Officer

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