We have conducted a pilot study to investigate the role of high-dose therapy and autologous bone marrow/stem cell transplantation (ASCT) during first complete or partial remission in 52 patients with poor-risk aggressive lymphoma. There were 42 patients with intermediate-grade or immunoblastic lymphoma who were considered to be high (60%) and high-intermediate risk (40%) groups at diagnosis based on the age-adjusted International Prognostic Index (IPI) and 10 patients with high-grade, SNCCL (small non-cleaved cell, Burkitt's, and non-Burkitt's), who at presentation had poor-risk features defined as elevated serum lactate dehydrogenase level, stage IV, and bulky mass >/=10 cm. The median age was 34 years (range, 16 to 56 years). Thirty-nine were transplanted in first complete remission and 13 in first partial remission after conventional therapy. Conditioning regimens consisted of total body irradiation (TBI) administered as a single fraction 750 cGy in 3 patients and in fractionated doses for a total of 1,200 cGy in 44 patients, in combination with 60 mg/kg etoposide and 100 mg/kg cyclophosphamide. Five patients with prior radiotherapy received 450 mg/m2 carmustine instead of TBI. Stem cell sources were either bone marrow and/or peripheral blood. No in vitro purging was used. All patients engrafted. Two SNCCL patients died of venoocclusive disease at 25 days and acute leukemia at 27 months posttransplantation. There were six relapses at 1.5 to 12.8 months posttransplantation. At a median follow-up of 44 months (range, 1 to 113 months), the estimated 3-year overall survival (OS) and disease-free survival (DFS) for all patients was 84% (95% confidence interval [CI], 70% to 92%) and 82% (95% CI, 68% to 91%), respectively. In the subset of patients with intermediate-grade and immunoblastic lymphoma, the 3-year DFS was 89% (95% CI, 74% to 96%) for all patients, 87% (95% CI, 67% to 96%) for high-risk patients, and 92% (95 CI, 61% to 99%) for high-intermediate risk patients. The 3-year OS and DFS for SNCCL patients were identical at 60% (95% CI, 30% to 84%). These results suggest that high-dose therapy and ASCT during first remission may improve the survival and prognosis of patients with poor-risk intermediate- and high-grade lymphoma. A prospective randomized study comparing high-dose therapy and ASCT with conventional chemotherapy in IPI high-risk patients with aggressive non-Hodgkin's lymphoma should be undertaken.