Chemotherapy combinations that include an alkylating agent and a platinum coordination complex have high response rates in women with advanced ovarian cancer. Such combinations provide long-term control of disease in few patients, however. We compared two combinations, cisplatin and cyclophosphamide and cisplatin and paclitaxel, in women with ovarian cancer. We randomly assigned 410 women with advanced ovarian cancer and residual masses larger than 1 cm after initial surgery to receive cisplatin (75 mg per square meter of body-surface area) with either cyclophosphamide (750 mg per square meter) or paclitaxel (135 mg per square meter over 24 hours). Three hundred eighty-six women met all the eligibility criteria. Known prognostic factors were similar in the two treatment groups. Alopecia, neutropenia, fever, and allergic reactions were reported more frequently in the cisplatin-paclitaxel group. Among 216 women with measurable disease, 73 percent in the cisplatin-paclitaxel group responded to therapy, as compared with 60 percent in the cisplatin-cyclophosphamide group (P = 0.01). The frequency of surgically verified complete response was similar in the two groups. Progression-free survival was significantly longer (P < 0.001) in the cisplatin-paclitaxel group than in the cisplatin-cyclophosphamide group (median, 18 vs. 13 months). Survival was also significantly longer (P < 0.001) in the cisplatin-paclitaxel group (median, 38 vs. 24 months). Incorporating paclitaxel into first-line therapy improves the duration of progression-free survival and of overall survival in women with incompletely resected stage III and stage IV ovarian cancer.