One hundred and forty male patients with ano-genital warts were randomly allocated to a double-blind study of 10% and 25% podophyllin in tincture of benzoin compound. One hundred and nine patients attended for a three-month period of surveillance. Only 24 (22%) patients were free of warts after having podophyllin treatment alone, 12 each after treatment with 10% and 25% podophyllin. There was no significant difference in the number of applications needed with each treatment. Neither hypersensitivity nor chemical ulceration occurred.