We have established a transformation system for entomopathogenic fungus, Metarhizium anisopliae, in order to develop mycoinsecticide by recombinant DNA techniques. Protoplasts of M. anisopliae would be transformed to a benomyl-resistant by introducing pBRG-4 plasmid DNA, which contains a β-tubulin gene of Aspergillus flavus conferring resistance to benomyl and a pyr4 gene of Neurospora crassa, in the presence of 5% polyethylene glycol and 10 mM calcium chloride. Transformants occuring at a frequency of 10 colonies per 50 ㎍ pBRG-4 DNA grew on the 5 ㎍/㎖ concentrations, of benamyl, while the wild type was inhibited by 2.5 ㎍/㎖. From the Southern analysis using genomic DNAs isolated from M. anisopliae transformants, the positive signals suggested that the β-tubulin gene had integrated in the M. anisopliae genome by homologous recombination.