Sixteen isolates of Microsporum equinum from cases of equine dermatophytosis in Finland, Sweden or Norway were studied mycologically. All the isolates produced typical macroconidia and were negative in the hair perforation test in vitro and were urease-positive. The growth pattern of M. equinum on polished rice greatly resembled that of M. audouinii during the first 2-3 weeks of incubation. All the isolates were incompatible with Nannizzia otae, the teleomorph of M. canis, but fresh M. equinum isolates showed growth stimulation against the (-) tester strain of N. otae. No cleistothecia or pseudocleistothecia were seen.