The anti-CD20 antibody rituximab improves the results of first-line therapy in aggressive non-Hodgkin's lymphoma (NHL) of B cell lineage. The purpose of this retrospective study was to evaluate its efficacy and toxicity in combination with the doxorubicine, methylprednisolone, high-dose cytarabine, cisplatin (ASHAP) protocol, an established treatment regimen for relapsed or refractory aggressive NHL. After a median of four cycles, 9 of 20 patients treated achieved a complete remission and 6 a partial remission, resulting in a total response rate of 75%. Remissions were not only seen in patients with relapsed lymphomas but also in patients with primary refractory or transformed indolent lymphomas. The outcome in cases with an international prognostic index score > or =2 was poor. Five of 15 responders received consolidating high-dose therapy with autologous stem cell transplantation. All of them are in ongoing remission. The main toxicity was myelosuppression, with neutropenias or thrombocytopenias of World Health Organization (WHO) grades III or IV developing in more than 90% of the cycles. There was one therapy-related death due to neutropenic sepsis. Non-hematologic toxicity was generally mild. At the time of analysis, six patients have died. After a median observation time of 17.5 months, the 2-year overall survival rate is 62%. ASHAP plus rituximab is an active and well-tolerated salvage protocol for patients with relapsed or refractory aggressive NHL, which compares favourably with other immuno-chemotherapy regimens, especially in patients with primary refractory or transformed indolent lymphomas.