We report the case of a 25-year-old, HIV-positive patient (group IV, A, C2 clinical stage) with a widespread dermatophyte infection. He was a male gypsy with a known history of intravenous drug abuse. After an episode of cerebral toxoplasmosis for which he was treated with systemic steroids (because of cerebral oedema) he developed, over 16 days, a remarkably extensive ringworm of the trunk due to an unusual zoophilic dermatophyte, Microsporum (Trichophyton) gallinae. Human infection with this dermatophyte species is unusual: there are as few as seven proven reported cases, all of whom had localized lesions. This is the first widespread and severe case reported in man and also the first reported from Spain.