To develop a method for the discrimination of basidiomycete species and strains with vegetative mycelia, DNAs isolated from the mycelia of Coprinus and Tricholoma strains, were subjected to random amplified polymorphic DNA (RAPD) analysis. Seven Coprinus species could be distinguished, clearly showing species-specific DNA patterns in the RAPD analysis. One specimen of unknown Coprinus strain was identified as C. cinereus by this method. Six strains of C. cinereus and 4 of C. angulatus could also be distinguished by the presence of strain-specific RAPD fragments. Five members of the Tricholoma family, T. matsutake and related 4 species, also showed species-specific DNA patterns in the RAPD analysis. The discrimination of Tricholoma species was confirmed by cluster analysis based on 192 RAPD fragments. The 5 species could be clearly divided into 5 groups in complete agreement with the taxonomic classification. RAPD analysis of mycelial DNA, as shown in these studies, is a suitable method for distinguishing basidiomycete species and strains.