To assess the effects of macrophage colony-stimulating factor (M-CSF) on platelet recovery in patients given chemotherapy for advanced and recurrent ovarian cancer, we selected 29 cases treated with carboplatin (280 mg/m2, Day 1) and cisplatin (70 mg/m2, Day 2). We evaluated the response and the platelet recovery effects of M-CSF, which was infused intravenously for 7 consecutive days after the second and fourth courses of chemotherapy. For the 54 courses of M-CSF infusion, the platelet nadir averaged 12.8 +/- 6.3 x 10(4)/microliters, with 9% of the courses designated Grade 3 or 4 on the toxicity scale, according to World Health Organization recommendations, both of which were significantly different from the M-CSF noninfused control courses (P < 0.05). The number of periods in which platelets were below 7.5 x 10(4)/microliters was significantly less in the courses of M-CSF infusion (P < 0.01). Response to treatment was pathologic complete in 23% and partial in 41%, for a total response of 64%. Cisplatin combined with carboplatin was effective in treating patients with advanced and recurrent ovarian cancer. M-CSF infusion may enhance the recovery from the thrombocytopenia that accompanies such chemotherapy.