A method is described for identifying strains of Metarhizium suitable for use in field experiments. It involves the restriction endonuclease digestion of a PCR product derived from the Pr1 protease gene and the analysis of the fragments by electrophoresis. Using this technique, 40 Metarhizium strains produced 15 different profile types and were clustered into four groups. Correlation between the profile of restriction fragments and geographic origin was observed for certain groups of strains. This PCR strategy allowed the identification of fungal strains, using as samples spores scraped from the surface of single insects killed by the fungus or single whole dead insects with external mycelium. The sequence of the Pr1 PCR product from two strains revealed that Pr1 gene has at least three introns.