CERTIFICATIONS PURSUANT TO SECTION 906
EX-99.906CERT

                                  CERTIFICATION

R. Jay Gerken, Chief Executive Officer, and Richard Peteka, Chief Financial
Officer of the Smith Barney Sector Series Inc. - Smith Barney Biotechnology
Fund, each certify to the best of his or her knowledge that:

1. The Registrant's periodic report on Form N-CSR for the period ended April 30,
2003 (the "Form N-CSR") fully complies with the requirements of section 15(d) of
the Securities Exchange Act of 1934, as amended; and

2. The information contained in the Form N-CSR fairly presents, in all material
respects, the financial condition and results of operations of the Registrant.

Chief Executive Officer                     Chief Financial Officer
Smith Barney Sector Series Inc. -           Smith Barney Sector Series Inc. -
Smith Barney Biotechnology Fund             Smith Barney Biotechnology Fund


/s/ R. JAY GERKEN                           /s/ RICHARD PETEKA
- ---------------------------                 ----------------------------
R. Jay Gerken                               Richard Peteka
Date: July 2, 2003                          Date: July 2, 2003

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 Smith Barney Sector Series Inc. -
Smith Barney Biotechnology Fund and will be retained by Smith Barney Sector
Series Inc. - Smith Barney Biotechnology Fund and furnished to the Securities
and Exchange Commission or its staff upon request.

This certification is being furnished to the Commission solely pursuant to 18
U.S.C. ss. 1350 and is not being filed as part of the Form N-CSR with the
Commission.