OBJECTIVE The aim of this prospective randomized trial was to examine the efficacy and safety of filgrastim after high-dose chemotherapy and autologous bone marrow transplantation (ABMT). METHODS Patients with poor-risk non-Hodgkin's lymphoma or relapsed Hodgkin's disease were treated in a randomized, open-label trial to study the use of filgrastim as an adjunct to high-dose chemotherapy and ABMT. Of 43 assessable patients, 19 were randomized to receive filgrastim by continuous subcutaneous infusion at a dose of 10 micrograms/kg/d, 10 to filgrastim 20 micrograms/kg/d, and 14 to a parallel control group that received no filgrastim after ABMT. RESULTS For all filgrastim-treated patients analyzed together, the median time to neutrophil recovery > or = 0.5 x 10(9)/L after the day of ABMT was significantly accelerated to 10 days compared with 18 days in control patients (P = .0001). The median number of platelet transfusions was identical in both groups. Clinical parameters, including the median number of days with fever (1 v 4, P = .0418) and neutropenic fever (5 v 13.5, P = .0001) were significantly shorter in the filgrastim than in the control group. The number of days on intravenous antibiotics and duration of hospitalization were also shorter in the treated groups; however, the differences did not reach statistical significance. For patients treated with the two different dose levels of filgrastim, the neutrophil recovery and clinical results were similar. Filgrastim-associated toxicity appeared to be minimal, with five adverse events considered at least possibly related to filgrastim: two in the higher-dose group and three in the lower-dose group. All of these were rated moderate, except one case of severe bone pain that did not preclude continued filgrastim treatment at a lower dose. Survival and relapse-free survival were similar for control and filgrastim-treated patients. CONCLUSIONS Taken together, the results of this first randomized study support the role of filgrastim given as an adjunct to ABMT in accelerating neutrophil recovery, as well as in reducing treatment-related morbidity and overall duration of the treatment procedure.