Although clear cell carcinoma of the ovary is considered to be a tumor with poor prognosis, the clinical characteristics has not been defined. The aim of this study was to evaluate the response of clear cell carcinoma of the ovary to first and second-line chemotherapy and explore effective chemotherapy. Fifty-three patients with clear cell carcinoma of the ovary were enrolled between 1988 and 1997 at our department. Since taxol was not available in Japan at that time, cisplatin-based combination chemotherapy has been exclusively used as a standard first-line chemotherapy. Retrospective analyses of clinical characteristics and the response to first or second-line chemotherapy were performed. Median age was 52 years (range 27-71 years). Tumors were 34% (18/53) stage I, 19% (5/53) stage II, 38% (20/53) stage III, and 9% (5/53) stage IV. All patients with I or II stage disease had optimal cytoreduction. Out of 25 patients with III or IV stage disease 20% (5/25) had negative residual tumor, 36% (9/25) had <2 cm residual tumor, and 44% (11/25) had >/=2 cm residual tumor. All patients received postoperative platinum-based chemotherapy. Of 23 patients with measurable residual tumor 8.7% (2/23) completely and 13% (3/23) partially responded to first-line chemotherapy consisting of cisplatin, adriamycin and cyclophosphamide (CAP) or cisplatin and cyclophosphamide (CP) by CT scan or second look laparotomy. Presence of endometriosis was 55% (29/53) but was not a prognostic factor. Although overall response rate of ovarian clear cell carcinoma to first-line chemotherapy by CAP or CP was about 22%, EP or EJ consisting of etoposide and cisplatin or carboplatin used as a second-line chemotherapy showed 29% response rate, while CPT-P consisting of CPT-11 and cisplatin showed 40% response rate. Clear cell carcinomas were frequently present at early stage, with association of endometriosis and with poor overall prognosis. Although patients with advanced ovarian clear cell carcinoma seemed to have better response to CPT-P than conventional platinum-based chemotherapy, further studies are required with larger number of patients to draw firm conclusions.