CERTIFICATIONS PURSUANT TO SECTION 302
EX-99.CERT

                                 CERTIFICATIONS

I, R. Jay Gerken, certify that:

1.      I have reviewed this report on Form N-CSR of Smith Barney Investment
        Series - SB Growth and Income Fund;

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-3(c) under the Investment Company Act of 1940) for
        the registrant and have:

        a)      Designed such disclosure controls and procedures, or caused such
                disclosure controls and procedures to be designed under our
                supervision, 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 and presented in this report our
                conclusions about the effectiveness of the disclosure controls
                and procedures, as of a date within 90 days prior to the filing
                date of this report based on such evaluation; and

        c)      Disclosed in this report any change in the registrant's internal
                control over financial reporting that occurred during the
                registrant's most recent fiscal half-year (the registrant's
                second fiscal half-year in the case of an annual report) that
                has materially affected, or is reasonably likely to materially
                affect, the registrant's internal control over financial
                reporting; and

5.      The registrant's other certifying officers and I have disclosed 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 and material weaknesses in the
                design or operation of internal control over financial reporting
                which are reasonably likely to adversely affect the registrant's
                ability to record, process, summarize, and report financial
                data; and

        b)      Any fraud, whether or not material, that involves management or
                other employees who have a significant role in the registrant's
                internal control over financial reporting.


Date:   July 8, 2004                             /s/ R. Jay Gerken
                                                 -------------------------------
                                                 R. Jay Gerken
                                                 Chief Executive Officer



I, Andrew B. Shoup, certify that:

1.      I have reviewed this report on Form N-CSR of Smith Barney Investment
        Series - SB Growth and Income Fund;

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 information included in this
        report, and the financial statements on which the financial information
        is based, 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-3(c) under the Investment Company Act) for the
        registrant and have:

        a)      Designed such disclosure controls and procedures, or caused such
                disclosure controls and procedures to be designed under our
                supervision, 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 and presented in this report our
                conclusions about the effectiveness of the disclosure controls
                and procedures, as of a date within 90 days prior to the filing
                date of this report based on such evaluation; and

        c)      Disclosed in this report any change in the registrant's internal
                control over financial reporting that occurred during the
                registrant's most recent fiscal half-year (the registrant's
                second fiscal half-year in the case of an annual report) that
                has materially affected, or is reasonably likely to materially
                affect, the registrant's internal control over financial
                reporting; and

5.      The registrant's other certifying officers and I have disclosed 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 and material weaknesses in the
                design or operation of internal control over financial reporting
                which are reasonably likely to adversely affect the registrant's
                ability to record, process, summarize, and report financial
                data; and

        b)      Any fraud, whether or not material, that involves management or
                other employees who have a significant role in the registrant's
                internal control over financial reporting.


Date:   July 8, 2004                             /s/ Andrew B. Shoup
                                                 -------------------------------
                                                 Andrew B. Shoup
                                                 Chief Administrative Officer