The efficacy of imiquimod in the treatment of external genital warts in HIV positive subjects was compared to a group of patients with normal immune function. Imiquimod 5% cream was applied by patients three times a week until resolution for a maximum of 16 weeks. Assessment for response and the occurrence of side effects was performed every four weeks. Thirty-one per cent of 75 HIV positive patients achieved a complete clearance, a partial response was obtained in 24% of subjects while in 45% we observed no clinical response. In the control group a total clearance was obtained in 62% of subjects, a partial response in 24% and no response in 14%. Recurrences occurred in 4/23 HIV patients and 2/31 immunocompetent patients within three months of follow-up. Side effects were minor to moderate. We conclude that imiquimod 5% cream has an acceptable efficacy and safety on HIV patients.