Microsporum canis is a ubiquitous dermatophyte that commonly causes human infections. Since contact with infected animals is the usual way of infection, tracing its source is an essential preventive measure. To type isolates of M. canis from human patients whose skin was affected, and from some animals (dogs and cats) that were closely associated to the patients. The inter-single-sequence-repeat-PCR (ISSR-PCR) technique has been used for typing 24 isolates of M. canis. Seventeen isolates tested were from human patients, 5 from cats and 1 from a dog A total of 21 genotypes were identified. The same genotype was found infecting a patient and a cat that was living closely with him, but another member of the same family proved to be infected with two genotypes different from that. Clinical specimens from two patients had been contaminated with the same genotype, probably in the laboratory where the samples were handled. These results demonstrate that ISSR-PCR polymorphism is a reliable method for the identification of the M. canis strains.