In our course of screening search for biologically active substances produced by entomopathogenic fungi, we isolated bassianolide as an insecticidal substance together with beauvericine from mycelia of a strain of Beauveria bassiana.1) In addition to these compounds, a new cyclodepsipeptide was isolated from mycelia of the same fungus. In this report we wish to describe structural elucidation of the new cyclodepsipeptide termed beauverilide A.