Recombinant leukocyte alpha interferon (rIFN-alpha A; Hoffmann-La Roche, Inc) was administered to 15 patients with recurrent or persistent ovarian carcinoma. All patients had been previously treated with surgery and combination chemotherapy including cyclophosphamide (15 patients), doxorubicin (14), and cisplatin (14). Three patient had also previously undergone radiation therapy. At the start of therapy the largest tumor size was less than or equal to 2 cm in four patients and greater than 2 cm in 11. Interferon was administered in three times weekly for 8 weeks at a dose of 20 X 10(6) units/m2, with average drug levels of 2267 pg/ml 6 hours after im injection. In three patients (20%), the dose had to be reduced by 50% because of drug toxicity. Side effects included fever (greater than 101 degrees F) in 12 patients, fatigue in ten, headache in two, diarrhea in two, and reversible myelosuppression in five. Of the 15 patients, one had mixed response lasting 12 weeks, two had stable disease of 8 weeks' duration, and 12 had disease progression.