Although the role of high dose chemotherapy (HDT) and autologous stem cell transplantation (ASCT) in the treatment of aggressive lymphoma has been established in several large prospective studies, its effectiveness in patients with peripheral T cell lymphoma (PTCL) has not been defined. We aimed to evaluate the efficacy of HDT and ASCT and prognostic factors for survival in patients with PTCL. We retrospectively analyzed the results of 40 PTCL patients treated with HDT and ASCT at Asan Medical Center between January 1995 and December 2005. Twenty patients had PTCL-U (peripheral T cell lymphoma, unspecified), 10 had extranodal natural killer/T cell lymphoma, 5 had anaplastic large cell lymphoma, 3 had angioimmunoblastic T cell lymphoma, 1 had hepatosplenic gammasigma T cell lymphoma, and 1 had disseminated mycosis fungoides. Disease status at transplant was complete response (CR)1 in 3 patients, CR2 or greater in 8, partial remission in 25, and refractory in 4. At a median follow-up of 16 months (range, 5 to 135 months) for surviving patients, the median overall survival (OS) was 11.5 months and the 1-year probability of survival was 46.1%. The median event free survival (EFS) was 3.6 months (95% confidence interval, 2.5 to 4.8 months). Ten patients (25%) remain alive without evidence of disease. The median OS of 11 patients with CR at ASCT was not reached; of these, 7 patients (63.6%) were alive with CR. In multivariate analysis, CR at ASCT was a prognostic factor for EFS (P = 0.025) and OS (P = 0.027) and normal lactate dehydrogenase (LDH) at ASCT was a prognostic factor for improved OS (P = 0.025). Chemosensitive patients with PTCL who achieved CR before ASCT seem to benefit from HDT and ASCT. Pretransplant values of LDH had potential to predict the survival.