In a phase I study to determine the maximum tolerated dose of paclitaxel (Taxol; Bristol-Myers Squibb Company, Princeton, NJ) given as a 3-hour infusion in combination with carboplatin administered every 21 days to women with advanced ovarian cancer, paclitaxel doses were escalated as follows: level 1, 135 mg/m2; level 2, 160 mg/m2; level 3, 185 mg/m2; and level 4,210 mg/m2. The fixed dose of carboplatin at levels 1 through 4 was given to achieve an area under the concentration-time curve (AUC) of 5 using the Calvert formula. In levels 5 and 6 the carboplatin dose was targeted at AUCs of 6 and 7.5, respectively, combined with a fixed paclitaxel dose of 185 mg/m2. To date, 30 previously untreated patients, all with a good performance status (Eastern Cooperative Oncology Group 0 to 2) have been entered into this ongoing study. The dose-limiting toxicity of the combination was myelosuppression (leukopenia, granulocytopenia, and thrombocytopenia). Neurotoxicity was largely moderate. So far, 14 patients are evaluable for response; of these, eight (57%) showed objective (complete or partial) response and disease stabilized in six patients. No patient had disease progression. We conclude that the combination of paclitaxel 185 mg/m2 administered as a 3-hour infusion followed immediately by a 1-hour infusion of carboplatin at an AUC of 6 can be administered safely in a 21-day schedule in the outpatient setting. The recommended dose for phase III studies is paclitaxel 185 mg/m2 and carboplatin AUC 6.