Pegfilgrastim is a pegylated form of a granulocyte colony-stimulating factor with a long half-life allowing for a single administration per chemotherapy cycle. The efficacy of a single dose of pegfilgrastim in supporting severely myelosuppressive regimens in previously treated cancer patients is unknown. Patients included in the present study had recurrent or refractory aggressive non-Hodgkin's lymphoma (NHL), had received two to three prior treatment regimens, and had good performance status and marrow reserve. Patients received intravenous paclitaxel 200 mg/m(2) on day 1 and topotecan 1 mg/m(2) daily for 5 days, repeated every 21 days for at least two cycles. On day 6, patients were given a single fixed dose of pegfilgrastim (6 mg) subcutaneously. Twenty patients were evaluable for analysis. After the first course of therapy, grade 4 neutropenia developed in all 20 patients. The median time to the neutrophil nadir was 9 days. The mean +/- SD duration of grade 4 neutropenia was 3.8 +/- 1.7 days. Nineteen (95%) patients received cycle 2 on time, on day 22. Five patients developed neutropenic fever (25%), which was associated with infection in one patient. In these previously treated patients with NHL, a single dose of pegfilgrastim was effective in promoting neutrophil count recovery after paclitaxel and topotecan, and allowed patients to receive the next planned dose on time.