Several prospective studies on dermatological findings in human immunodeficiency virus (HIV) type 1 infected patients have been published, mostly in populations in which the predominant risk factor for HIV infection is homosexuality. We attempted to identify cutaneous diseases associated with HIV-1 infection and to assess disease progression in a cohort of Spanish patients in whom the predominant cause of HIV infection was intravenous drug abuse. We prospectively examined 1161 HIV-1-positive patients for 38 months. Seventy-four per cent of patients were intravenous drug abusers, whereas heterosexual contact was the only risk factor in 14% and homosexuality in 9%. Centers for Disease Control stage II disease predominated (51%), whereas stage IV disease was less frequent (39%). The mean CD4 count was 353/mm3. We took patients' past and present medical history and performed a complete physical examination as well as taking photographs and carrying out the necessary diagnostic procedures. CD4 counts/mm3 were measured at each visit. A diagnosis of cutaneous disease was made in 799 patients (69%). Oral candidiasis and seborrhoeic dermatitis were the most common skin disorders, followed by xerosis, drug eruptions, dermatophytosis and the papular eruption of acquired immunodeficiency syndrome. Condyloma acuminatum, herpes zoster and herpes simplex were the most frequent viral infections. Conditions that have a statistically significant association with advanced stage and low CD4 levels include drug eruptions, xerosis, light reactions, diffuse alopecia, herpes simplex, oral candidiasis, psoriasis, oral hairy leucoplakia, molluscum contagiosum, Kaposi's sarcoma, furuncles, candidal intertrigo, folliculitis and ungual infection, as well as onychomycosis and tinea pedis or manuum. Dermatoses commonly associated with homosexuality, such as Kaposi's sarcoma and oral hairy leucoplakia, were rare in our patients.