Patient-applied formulations of 0.5% podofilox (podophyllotoxin) were evaluated for the treatment of external genital warts in a double-blind, placebo-controlled study. Seventy-two women were enrolled and, using a randomized, computer-generated list, assigned to receive either active drug or placebo in a 2:1 ratio. Patients were instructed to apply the medication to their external warts twice each day for 3 consecutive days, followed by 4 days without treatment. This cycle was repeated at weekly intervals for a maximum of 4 weeks (and a minimum of 2 weeks). Patients were evaluated weekly for the first month and then at weeks 6 and 10. The number of warts present was recorded and the overall improvement was assessed. The treated area was examined, the patients were questioned about any adverse effects, and standard hematologic/biochemical studies were conducted. The final results showed that podofilox cleared 74% of the total wart count, compared with an 18% regression in the placebo group (P less than .001). The investigators' assessments of improvement correctly distinguished active drug from placebo at every observation point. Local untoward effects were minor and transient. There was no evidence of systemic effects. It is concluded that patient-applied podofilox is a safe and effective therapy for genital condylomata in women. When available, this drug will simplify the treatment of genital warts by providing a patient-applied alternative therapy.