In order to determine the activity of paclitaxel in patients with relapsed or refractory non-Hodgkin's lymphoma (NHL), we conducted a phase II clinical trial in which eligible patients received paclitaxel 200 mg/m2 intravenously over 3 h. Treatment was repeated every 3 weeks. Patients achieving complete or partial responses after two courses of paclitaxel continued to receive therapy for a maximum of eight courses, otherwise they were removed from the study. Of 96 evaluable patients, 45 (47%) had primary refractory disease, and 51 (53%) had relapsed lymphoma. The median number of prior treatment regimens was two (range one to 10 regimens). 45 patients had lowgrade, 44 had intermediate-grade, and seven had mantle cell lymphoma. 24/96 patients responded (10 complete and 14 partial remissions) for an overall response rate of 25% (95% CI 17-35%). Patients with relapsed lymphoma had a higher response rate than those with primary refractory disease (19/51 = 37% v 5/45 = 11%; P < 0.01), and patients with relapsed intermediate-grade lymphoma had a higher response than those with relapsed low-grade lymphoma (9/18 = 50% v 10/31 = 32%; P = 0.22). The treatment was very well tolerated with the most common side-effects being alopecia (100%), peripheral neuropathy (35% of > or = grade II), and arthralgia/myalgia (25% of > or = grade II). After the first course of paclitaxel, grade III/IV thrombocytopenia and neutropenia were observed in 21% and 23% of the patients respectively. 23 episodes of neutropenic fever developed after 250 courses of paclitaxel therapy (8%). We conclude that paclitaxel, at this dose and schedule, is an active new drug for the treatment of non-Hodgkin's lymphoma. The activity of paclitaxel combination programmes are currently under investigation.