Therapy of persistent human papillomavirus disease with two different interferon species. Consensus interferon and interferon alfa-2a were used to treat patients with persistent human papillomavirus disease. Thirty-one patients were treated with either consensus interferon or a placebo (25 received active drug and 6 received placebo), and 24 patients were treated with interferon alfa-2a. Of the 25 patients who received consensus interferon, 19 (76%) showed either complete or partial clearing of condyloma 10 and 16 weeks after initiation of therapy; in 22 of the 24 patients (91%) who received interferon alfa-2a, clearing was demonstrated after a similar time period. Thirty of 34 patients who had no response or a partial response requested additional therapy, and 20 of these patients treated with adjunctive therapy had a complete response. The results of this study support the efficacy of both interferons in the treatment of overt condyloma acuminatum and suggest that interferon enhances subsequent adjunctive therapy. 