The optimal therapy for patients with relapsed indolent B-cell non-Hodgkin's lymphoma is unclear. Combination chemotherapy such as CHOP (cyclophosphamide, doxorubicin, vincristine, prednisolone) or purine analogues including fludarabine are frequently used and the anti-CD20 monoclonal antibody rituximab has recently been licensed for use. However, no comparative studies of these therapies have been reported. Since relapsed indolent B-cell NHL is generally regarded as incurable with current therapies, the place of each of these therapies is likely to be determined by their relative efficacy, toxicity and cost. We undertook a literature review and a retrospective analysis of patients receiving combination chemotherapy for relapsed indolent B-cell NHL at our institution to determine the response rates and the duration of response when treated with CHOP or fludarabine. Reported response rates and median response duration for these regimens are similar, and similar to those reported in phase II studies of rituximab. A cost minimization analysis was therefore conducted. The per patient costs for the treatment of drug-related adverse events were pound 5049 for CHOP, pound 2953 for fludarabine and pound 109 for rituximab. When costs of a full course of each treatment were compared, the costs per patient for CHOP, fludarabine and rituximab were pound 7210 (pound 5975-8445), pound 10022 (pound 8917-11126) and pound 6080 (pound 5892-6267) respectively. In this preliminary analysis, rituximab appeared to have a similar efficacy rate to CHOP and fludarabine, but had significantly fewer adverse events and a lower total cost per patient. These data require confirmation in a prospective randomized study with formal assessment of cost-effectiveness.