In a non-randomized clinical trial, combined intraperitoneal therapy with recombinant interferon alpha-2b (20-50 MU) and mitoxantrone (20-50 mg) was studied for recurrent ovarian cancer with ascites. Altogether 19 patients were treated. After primary operation, all patients had received intravenous chemotherapy, 16 of which included cisplatin. One patient had complete response, seven patients partial response, four no change and seven progressive disease. The mean duration of the responses was 5+ months (range 1-12), and mean survival time 4.5+ months (range 1-14+). Eight patients had side effects (flu-like symptoms, dyspnea, abdominal pain, vomiting, diarrhea, fever and bowel obstruction). It was concluded that the formation of ascites in refractory ovarian cancer can be reduced with intraperitoneal administration of interferon alpha-2b and mitoxantrone, with tolerable side effects.