TAXOL (paclitaxel), a new cytotoxic agent of the taxane class, has demonstrated activity against ovarian cancer. To address questions of a dose-response effect and the value of premedication to prevent hypersensitivity reactions during brief TAXOL infusions, a trial with a 2 x 2 factorial design was begun in patients with relapsed ovarian cancer. From July 1991 through March 1992, 407 patients who had failed one or two prior platinum regimens and who had measurable or evaluable disease were randomized to either 175 or 135 mg/m2 TAXOL administered by either 24- or 3-h infusion. Premedication to prevent hypersensitivity reactions, consisting of steroids, antihistamines, and H2-blockers, was administered to all patients before TAXOL. Toxicity and response data on 298 and 286 patients, respectively, are presented. Overall response rate was 18.5% (53 of 286 patients, 95% confidence interval 13.9% to 23.2%). The results suggest that TAXOL can be given safely over 3 h with premedication. Neutropenia appears to be related more to schedule than to dose, although neuropathy is primarily dose-related. Responses occurred more frequently in those who received 175 mg/m2, but analysis of all accrued patients is necessary before a final conclusion can be drawn. Studies administering TAXOL over 3 h at maximally tolerated doses are warranted.