Twenty-five patients with a variety of histologic types of advanced non-Hodgkin's lymphoma refractory to previous chemotherapy were entered into a trial of vincristine infusion. Patients received 5-day courses of vincristine 0.25 mg/m2/day by continuous intravenous infusion after an initial 0.5 mg intravenous bolus injeciion. Courses were repeated every 3 weeks. Objective responses were observed in nine patients (36%), all of whom had previously received vincristine given by conventional bolus injection. A complete response occurred in a patient with diffuse mixed histiocytic lymphocytic lymphoma, and partial responses were observed in eight patients with the following histologic types: diffuse poorly differentiated lymphocytic (4); nodular poorly differentiated lymphocytic (2); diffuse mixed histiocytic lymphocytic (1); and diffuse histiocytic (1). Duration of response lasted from 1.2 to 16.2 months (mean, 4.4 months). The principal complication of therapy was mild-to-moderate neurotoxicity; this occurred in 12 patients (48%) who received a total of 54 courses of vincristine infusion. Hematologic toxicity was minimal and nausea/ vomiting did not occur. Vincristine infusion may afford palliation for patients with advanced non-Hodgkin's lymphomas who have become refractory to standard chemotherapeutic regimens even if they have received prior vincristine by conventional bolus injection. These data suggest the possibility of enhancing the therapeutic efficacy of vincristine in the treatment of non-Hodgkin's lymphoma by use of an infusion technique.