During the last 4 years, 88 patients with low-grade non-Hodgkin's lymphoma have received fludarabine, 25 mg/m2 daily for 5 days, repeated every 3 to 4 weeks. Fifty-one patients received fludarabine at recurrence or when the disease was deemed resistant to conventional treatment, 21 patients received the drug in the context of "minimal residual disease" in the hope of complete remission being achieved with a view to proceeding to myeloablative therapy (cyclophosphamide and total body irradiation) with autologous bone marrow transplantation, and 16 newly diagnosed patients received fludarabine as first-line therapy. Myelosuppression was the predominant toxicity, with 55% and 31% of previously treated and newly diagnosed patents, respectively, becoming neutropenic (neutrophils < or = 1.0 X 10(9)/L). The response rate (complete and partial response) was 44% for both patients with recurrent/resistant disease (20 of 45 evaluable patients) and for those with "minimal residual disease" (nine of 20 evaluable patients). In newly diagnosed patients, the response rate was 69% (11 of 16 patients). Five patients died of infection while neutropenic. These results confirm the activity of fludarabine in low-grade non-Hodgkin's lymphoma. Its precise role remains to be determined.