A phase III study was conducted comparing intraperitoneal (ip) versus intravenous (iv) cisplatin-based therapy for patients with newly diagnosed ovarian cancer to determine if the pharmacologic advantage of ip delivery could be translated into an improved response and survival rate. Twenty-nine patients were randomized to receive six cycles of ip cisplatin 200 mg/m2 plus ip etoposide 350 mg/m2 with iv thiosulfate protection given every 4 weeks; thirty-three patients were randomized to receive six cycles of iv cisplatin 100 mg/m2 plus iv cyclophosphamide 600 mg/m2 administered every 3 weeks. Patients were stratified by stage (IIC-IV) and size of residual disease (> or < or = 1 cm). The study was conducted in a community-wide setting. The complete response in evaluable patients was 48% in the ip group and 52% in the iv group. The surgical complete response rate for all patients on study, underestimated because not all patients in complete clinical remission had a second-look laparotomy, was 31% in the ip group and 33% in the iv group. There was no difference in the response rates between the treatment arms as a function of residual disease < or = or > 1 cm. With a median follow-up of 46 months (range 21-70 months) there is no difference in response duration or survival. Both regimens were well tolerated with comparable hematologic and nonhematologic toxicity.