Microsporum nanum (Fuentes, Aboulafia & Vidal) Fuentes was first isolated in Cuba in 1954 and was described by Fuentes et al. (12) as a variant of M. gypseum (Bodin) Guiart & Grigorakis. These workers isolated the fungus from a scalp lesion of an eight-year-old boy. Hair invasion was described as being of the endothrix type. On Sabouraud dextrose agar the isolate produced a white, cottony colony that became granular and buff-colored. The reverse side was brownish-red. Microscopically, numerous small, pear-shaped, thickwalled, finely verrucose or occasionally smooth twoor three-celled macronidia were formed. These spores had truncate bases and ranged in size from 12-18 x 4-7.5 p. Microconidia were present in low numbers in the Sabouraud agar cultures. On soil-hair plate cultures numerous microconidia as well as macroconidia were formed. The hair filaments in this type of culture were pierced by perforating organs. This isolate was considered, at first, to be a variant of M. gypseum and named M. gypseum var. nana Fuentes, Aboulafia & Vidal. Seven months after obtaining the first isolate, Fuentes studied a second culture recovered from the glabrous skin of an adult (10, 11). On the basis of the stability of the two isolates and the striking nature of the macroconidia, the organism was formally described as a new species and named M. nanunm. Published reports of isolations of this striking dermatophyte from humans have been rare. Aside from Fuentes' report from Cuba, isolations of M. nanum have been recorded in Mexico (2), the United States (3), and Canada (6).