CDDP was intraperitoneally administered to 45 ovarian cancer patients (9 cases in Stage Ic, 9 cases in Stage II, 19 cases in Stage III and 8 cases in Stage IV) as the first line chemotherapy to examine response rates and cumulative survival rates by Kaplan-Meier method. Among 18 cases with measurable tumor, there were 5 CR cases, 6 PR cases, 4 NC cases and 3 PD cases. Eleven out of 18 responded, for a response rate of 61.1%. The 3- and 5-year survival rates were 88.9% and 88.9% in Stage I, 46.7% and 0% in Stage II, 48.6% and 41.7% in Stage III, and 0% and 0% in Stage IV, respectively. The 3- and 5-year survival rates in patients with residual tumor smaller than 2 cm in diameter after the first surgery in Stage III or IV were 76.9% and 61.4% respectively, in contrast to 11.5% and 11.5% in patients with residual tumor of 2 cm or larger in diameter. Thus, a significantly better prognosis was demonstrated in patients with residual tumor smaller than 2 cm. These results indicate that intraperitoneal administration of CDDP demonstrated high response rates and proved to be useful as the first line chemotherapy, yet did not manage to improve the long-term prognosis of patients with progressive cancer.