A fusion protein vaccine consisting of human papillomavirus 6 L2E7 with Alhydrogel was developed for the treatment of genital warts. Twenty-seven subjects with genital warts received 3 immunizations over 4 weeks in an open-label study. The vaccine was well-tolerated, and all subjects made serum IgG antibodies, predominantly IgG1, against L2E7. Nineteen of 25 tested persons made antigen-specific T cell proliferative responses to L2E7, and peripheral blood mononuclear cells when cultured with L2E7 in vitro produced both interferon-gamma and interleukin (IL)-5, although IL-5 predominated after the final vaccination. Five subjects completely cleared warts within 8 weeks. Subjects whose warts were not cleared by 8 weeks were offered conventional therapy. Recurrence of warts was not seen in any of the 13 persons whose warts cleared by vaccine alone or with conventional therapy. While these preliminary results of the use of this therapeutic immunogen are encouraging, proof of efficacy will require randomized double-blind trials.