Eighteen patients with residual epithelial ovarian cancer at second-look laparotomy were treated with a combined total of 210 cycles of intraperitoneal cis-platinum. Sixteen patients had previously received cis-platinum containing combination chemotherapy systemically. Seven patients had microscopic residual disease at the start of intraperitoneal therapy, eight had macroscopic disease of 5 mm in diameter or less, and three had disease of 6-10 mm in diameter. The drug was administered weekly in 2 L of Ringer's lactate solution via an indwelling Tenckhoff catheter, and the dose ranged from 30-270 mg per cycle (median 120 mg). The dwell time was 20 minutes. After 12 cycles, response was assessed by open laparoscopy (six patients), laparotomy (eight patients), or peritoneal cytology (three patients). One patient developed distant metastases. Local and systemic toxicity was mild. Delays of therapy were necessary for eight of the 210 cycles because of hematologic toxicity. Of the 15 patients available for pathologic evaluation, four (26.6%) had a complete response and two (13.3%) had a partial response. Results of this pilot study suggest a possible role for intraperitoneal cis-platinum in the management of carefully selected patients with epithelial ovarian cancer.