This study retrospectively compared nedaplatin and irinotecan hydrochloride (NDP/CPT) combination therapy with cisplatin and irinotecan hydrochloride therapy (CDDP/CPT) for efficacy and adverse events in the treatment of clear cell adenocarcinoma of the ovary (CCC) and recurrent ovarian carcinoma. A total of 115 patients were included in the present study. NDP/CPT was administered intravenously every 4 weeks (NDP, 60 mg/m(2) on day 1; CPT, 50 mg/m(2) on days 1, 8 and 15). CDDP/CPT was also administered intravenously (CDDP, 60 mg/m(2) on day 1; CPT, 60 mg/m(2) on days 1, 8 and 15). Patients with primary CCC were treated with NDP/CPT in 29 cases and CDDP/CPT in 20 cases. Patients with recurrent ovarian carcinoma were treated with NDP/CPT and CDDP/CPT in 33 cases each. No significant difference was observed in the 5-year overall survival (OS)/progression-free survival (PFS) of patients with primary CCC, with the exception of those patients with stages Ia and Ic(b) who underwent NDP/CPT and CDDP/CPT treatments (OS: 58%, PFS: 40% and OS: 53% and PFS: 47%, respectively). No significant differences were found in the response rates to NDP/CPT and CDDP/CPT in patients with recurrent ovarian carcinoma (27 and 18%, respectively). Similarly, there were no significant differences in the 5-year OS and PFS of patients with recurrent ovarian carcinoma treated with NDP/CPT or CDDP/CPT (OS: 15%, PFS: 3% and OS: 18%, PFS: 6%, respectively). In terms of the hematological toxicity of grade 3 or above and non-hematological toxicity of grade 2 or above in patients treated with NDP/CPT and CDDP/CPT, respectively, neutropenia was 23 and 56%; anemia, 1, and 20%; thrombocytopenia, 0 and 5%; nausea, 20 and 52%; diarrhea, 14 and 25%; and fever, 2 and 11%. Accordingly, NDP/CPT indicated mild toxicity, and was therefore equally effective and less toxic than CDDP/CPT in the treatment of primary CCC and recurrent ovarian carcinoma.