CERTIFICATIONS PURSUANT TO SECTION 906

EX-99.906CERT

CERTIFICATION

R. Jay Gerken, Chief Executive Officer, and Frances M. Guggino, Chief Financial Officer of Legg Mason Partners Investment Series – Legg Mason Partners Variable Premier Selections All Cap Growth Portfolio (the “Registrant”), each certify to the best of his knowledge that:

1. The Registrant’s periodic report on Form N-CSR for the period ended April 30, 2006 (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
Legg Mason Partners Investment Series -	Legg Mason Partners Investment Series –
Legg Mason Partners Variable Premier Selections	Legg Mason Partners Variable Premier Selections
All Cap Growth Portfolio	All Cap Growth Portfolio
/s/ R. Jay Gerken	/s/ Frances M. Guggino
R. Jay Gerken	Frances M. Guggino
Date: July 7, 2006	Date: July 7, 2006

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

CERTIFICATIONS PURSUANT TO SECTION 906

EX-99.906CERT

CERTIFICATION

R. Jay Gerken, Chief Executive Officer, and Frances M. Guggino, Chief Financial Officer of Legg Mason Partners Investment Series – Legg Mason Partners Variable Dividend Strategy Portfolio (the “Registrant”), each certify to the best of his knowledge that:

1. The Registrant’s periodic report on Form N-CSR for the period ended April 30, 2006 (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
Legg Mason Partners Investment Series -	Legg Mason Partners Investment Series –
Legg Mason Partners Variable Dividend Strategy Portfolio	Legg Mason Partners Variable Dividend Strategy Portfolio
/s/ R. Jay Gerken	/s/ Frances M. Guggino
R. Jay Gerken	Frances M. Guggino
Date: July 7, 2006	Date: July 7, 2006

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

CERTIFICATIONS PURSUANT TO SECTION 906

EX-99.906CERT

CERTIFICATION

R. Jay Gerken, Chief Executive Officer, and Frances M. Guggino, Chief Financial Officer of Legg Mason Partners Investment Series – Legg Mason Partners Variable Growth and Income Portfolio (the “Registrant”), each certify to the best of his knowledge that:

1. The Registrant’s periodic report on Form N-CSR for the period ended April 30, 2006 (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
Legg Mason Partners Investment Series -	Legg Mason Partners Investment Series –
Legg Mason Partners Variable Growth and Income Portfolio	Legg Mason Partners Variable Growth and Income Portfolio
/s/ R. Jay Gerken	/s/ Frances M. Guggino
R. Jay Gerken	Frances M. Guggino
Date: July 7, 2006	Date: July 7, 2006

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

CERTIFICATIONS PURSUANT TO SECTION 906

EX-99.906CERT

CERTIFICATION

R. Jay Gerken, Chief Executive Officer, and Frances M. Guggino, Chief Financial Officer of Legg Mason Partners Investment Series – Legg Mason Partners Variable Government Portfolio (the “Registrant”), each certify to the best of his knowledge that:

1. The Registrant’s periodic report on Form N-CSR for the period ended April 30, 2006 (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
Legg Mason Partners Investment Series -	Legg Mason Partners Investment Series –
Legg Mason Partners Variable Government Portfolio	Legg Mason Partners Variable Government Portfolio
/s/ R. Jay Gerken	/s/ Frances M. Guggino
R. Jay Gerken	Frances M. Guggino
Date: July 7, 2006	Date: July 7, 2006

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