Twenty-three Rhizomucor isolates were characterized by random amplified polymorphic DNA-PCR (RAPD-PCR) with 10-bp oligonucleotide primers. These data were used for numerical analyses to obtain information on the intraspecific genetic polymorphism of Rhizomucor species. The genetic variability in Rhizomucor pusillus and Rhizomucor miehei isolates was found to differ; the latter revealed less intraspecific polymorphism. The different levels of genotypic diversity suggest a correlation with the different forms of mating behaviour of these species. Rhizomucor tauricus displayed amplification patterns similar to those of the investigated R. pusillus strains, reinforcing the assumption that R. tauricus does not represent a separate species. Characteristic RAPD markers allowing PCR-based species identification of Rhizomucor isolates were determined.