We report on the first human infection with Trichophyton equinum in Germany, which was transmitted from an infected pony to a 12-year old girl. Trichophyton equinum was identified by its morphology, dependency on nicotinic acid, hair perforation, and enzyme production. A noteworthy new observation was the development of white pleomorphic tufts on the surface of thalli grown on potatoe-dextrose agar. The girl's tinea was non-inflammatory and responded promptly to topical treatment, whereas the pony's strongly inflammatory lesions persisted for months. In supernatants of cultures supplemented with different nutrients, enzyme patterns were measured for Trichophyton equinum that correspond to other species of dermatophytes more pathogenic for humans. Therefore, a lack of enzymes is apparently not the explanation for the rarity of human infections with Trichophyton equinum. More likely, predisposing factors of the host are necessary in combination with a close contact to infected horses. Treatment of infected humans appears to be no major problem.