We report nine children with relapsed (n = 8) or high-risk (n = 1) peripheral T-cell lymphoma (PTCL) who underwent autologous (n = 6) or allogeneic (n = 3) bone marrow transplantation (BMT). These children received transplants as part of a prospective phase I/II study of thioTEPA (TT) and total body irradiation (TBI) with escalating doses of VP-16. The median age of these patients at time of BMT was 6.5 years (range 2.5 years to 14 years). Three were transplanted with active disease after failing salvage chemotherapy. Of the other six, one was transplanted in first complete remission (CR) and five in second or subsequent CR. Of these nine patients, eight are free of disease a median of 25 months after BMT (range, 6 to 48 months), with an estimated 2-year relapse-free survival (RFS) of 89%. Six of these eight patients have been followed for 12 or more months after BMT, and in each their current remission exceeds their longest previous remission duration. The toxicity of the TT/TBI +/- VP-16 regimens was significant but manageable, predominantly consisting of severe mucositis. For a comparison, we reviewed retrospective data on the six additional children and adolescents with PTCL who underwent BMT during the 3-year period preceding this phase I/II study. The median age at BMT of these six patients was 19 years (range 15.5 years to 20 years). These patients were prepared for BMT with a variety of other regimens. One had no response to BMT and the other five relapsed at 1.5 to 5 months after BMT (median, 3 months) with an RFS of 0%. Our data suggest that thioTEPA plus TBI, with or without VP-16, is an effective preparative regimen for BMT for young patients with relapsed or high-stage PTCL and leads to prolonged RFS.