Eight patients with basal cell carcinomas were treated with recombinant alpha-2 interferon. Each patient had a biopsy-proved basal cell carcinoma of the nodular or superficial type that was injected intralesionally three times a week for 3 weeks (9 total injections) with 1.5 X 10(6) IU (0.15 ml) of alpha-2 interferon per injection (total dose, 13.5 X 10(6) IU). Excisional biopsy 2 months after completion of therapy revealed no evidence of basal cell carcinoma in any patient. Minimal side effects were observed. In these eight patients alpha-2 interferon was therefore an effective and safe modality of treatment. The encouraging results of this pilot study suggest that additional evaluation of interferon in the treatment of basal cell carcinoma is warranted.