The current initial standard chemotherapy for advanced ovarian cancer is a regimen with a combination of platinum and taxane. However, the 5-year survival rate remains at 40% or lower, and the recurrence rate is as high as 70-80%. Second-line chemotherapy for recurrent cases has not yet been established. We conducted a phase I study of combined chemotherapy with paclitaxel (TXL) and carboplatin (CBDCA) administered weekly for recurrent and refractory ovarian cancer. The subjects were patients with a histopathologically confirmed diagnosis of malignant epithelial ovarian cancer, with recurrent or refractory disease after the initial chemotherapy. TXL was administered at escalating concentrations up to 60-100 mg/m(2), while the dose of CBDCA was fixed at an AUC of 2. In regard to the dosing schedule, premedication was performed as defined before TXL administration, and TXL and CBDCA were administered, in that order, by intravenous infusion for over at least 1 hour. The 4-week period, including the administration of both drugs on Day 1, 8, and 15, was regarded as one course of treatment. No cases developed grade 4 hematoxicity, but leukopenia and neutropenia occurred. All cases of leukopenia of step 4 and step 5 developed grade 3 leukopenia. Grade 2 thrombocytopenia was one example at a low rate. Non-hematological toxicity included neuropathy, arthralgia and muscle pain, but none of the patients developed grade 3 or 4. The response rate was 41.7% (5/12). The response rate of cases administered over TXL 80 mg was 66.7% (4/6). Based on these results,the following dose schedule was recommended for planning and designing a phase II study in the future: CBDCA AUC 2+TXL 80 mg/m(2) (Days 1, 8, and 15 q 4 weeks).