Species-specific primers were designed from nucleotide sequences of the chitin synthase 1 gene (CHS1) of Arthroderma benhamiae, A. simii and A. vanbreuseghemii. The A. benhamiae-specific primer amplified a 560-bp fragment from A. benhamiae but not from ii. simii and A. vanbreuseghemii. The A. simii-specific primers amplified a 470-bp fragment from A. simii but not from ii. benhamiae and A. vanbreuseghemii. The A. vanbreuse-ghemii-specific primers amplified a 360-bp fragment from A. vanbreuseghemii but not from A. benhamiae and A. simii. With these species-specific primers of CHS1 genes, 10 clinical isolates from humans and animals were examined by polymerase chain reaction analyses. These isolates pros ed to be identical to A. vanbreuseghemii.