Intensive therapy, mainly with purged autologous bone marrow transplantation (ABMT), has been proposed in recent years as consolidation treatment in young patients with follicular lymphoma. Reported experience with transplantation of peripheral blood progenitor cells (PBPC) is, so far, limited. The feasibility and the therapeutic efficacy of intensive therapy followed by unpurged autologous PBPC reinfusion were evaluated in 60 patients with poor-prognosis follicular lymphoma. Twelve patients were in first partial remission (PR), 34 were in second partial or complete remission (CR), and 14 were in subsequent progression. At the time of the procedure, 39 patients (65%) had persistent bone marrow involvement, 49 patients (82%) were in PR, and 16 patients had presented with a histologic transformation (HT). PBPC were collected after chemotherapy followed by granulocyte (G) colony-stimulating factor (CSF) or granulocyte-macrophage (GM)-CSF in 50 patients. Conditioning regimens included high-dose chemotherapy alone (14 patients); mainly the BCNU, etoposide, aracytine, melphalan [BEAM] regimen), or cyclophosphamide with or without etoposide plus total body irradiation (46 patients). The median time to reach a neutrophil count greater than 0.5 x 10(9)/L was 13 days. There were five treatment-related deaths, with four being associated with a delayed engraftment and all occurring in patients in third or subsequent progression. At a median follow-up of 21 months, 48 patients were still alive, 18 relapsed, and seven died of lymphomas progression. Estimated 2-year overall survival (OS) and failure-free survival (FFS) rates were 86% and 53%, respectively, without or plateau. Patients treated in PR1 or PR2/CR2 had a significantly longer rate of OS and FFS than those treated in subsequent progression (P = .002 and P = .001, respectively), whereas age, response to salvage treatment, presence or absence of residual bone marrow involvement, or conditioning regimen had no influence on outcome. Patients with HT tended to have a worse FFS rate (P = .04) without an OS difference. Along with an unusual rate of engraftment failure, the poor FFS observed in heavily pretreated patients suggests that intensive therapy should be performed early in the course of the disease. Given the high percentage of patients intensified in PR with residual bone marrow involvement, our results are comparable with those achieved with ABMT published to date. Prospective trials are warranted to compare this strategy with standard therapy in patients with relapsing or PR follicular lymphoma.