Gliovirin1* (1) and the related antibiotic, gliotoxin2) (2), are produced by P- and Q-strains, respectively, of the fungus Gliocladium virens3). G. virens is an effective biocontrol agent of several seedling and soilborne plant diseases4~6), and gliovirin and gliotoxin have been linked to G. virens efficacy as a biocontrol agent of seedling diseases incited by Pythium ultimum and Rhizoctonia solani, respectively3). The biosynthesis of gliotoxin has been extensively investigated, but that of gliovirin has not. During the isolation of gliovirin, l,lphenylalanine anhydride was also isolatedx\ Based on this observation, we hypothesized that lphenylalanine was the biosynthetic precursor of gliovirin. We now confirm this hypothesis.