A multicentre phase II trial was conducted to evaluate the efficacy and toxicity of gemcitabine in patients with refractory or relapsed indolent non-Hodgkin's lymphoma. Thirty-six patients were enrolled onto the study, including 11 cases of mantle cell lymphoma (MCL), 10 cases of chronic lymphocytic leukaemia (CLL)/lymphocytic lymphoma, nine cases of follicular lymphoma, four cases of lymphoplasmacytic lymphoma and two cases of T-cell lymphoma. Gemcitabine 1 g/m(2) was administered as a 30-min infusion on d 1, 8 and 15 of a 28-d schedule, up to a maximum of six cycles. Complete responses were observed in two patients with MCL, and partial responses were observed in seven patients, including three patients with CLL/lymphocytic lymphoma, two patients with T-cell lymphoma, one patient with MCL and one patient with follicular lymphoma. Minor responses were observed in three patients, including two patients with MCL and one patient with CLL. The median duration of response was 150 d and the overall progression-free survival was 342 d. Haematological toxicity was observed as grade 3-4 leucopenia in 12 patients (33%) and grade 3-4 thrombocytopenia in 18 patients (50%). Severe non-haematological toxicity included one case of fatal veno-occlusive disease, one case of thrombotic microangiopathy leading to terminal renal failure, one case of capillary leak syndrome, one case of myocardial infarction and drug-induced fever in two patients. These data suggest that gemcitabine displays activity in patients with MCL and CLL/lymphocytic lymphoma. Haematological toxicity was frequent in these heavily treated patients. Severe non-haematological toxicity was significant and should be taken into account in the design of future trials.