12 patients suffering from psoriasis were given recombinant interferon (IFN)-alpha-2c at a daily dosage of 2.5 X 10(6) or 5 X 10(6) IU for up to 4 weeks by the intramuscular route. One patient showed complete regression and remained free of lesions after 12 months of follow-up. Three patients were judged as partial remission with stop of scale formation and flattening of skin lesions. No beneficial effect was seen in 8 patients. Side effects due to IFN-alpha application, such as fever, headache, malaise, and chills disappeared with subsequent treatments. Our findings suggest a possible positive effect of IFN-alpha in psoriasis.