Anaplastic large cell lymphoma (ALCL) is a heterogeneous family of lymphoid tumours, among which the T and null cell types were recently listed in the REAL classification as a distinct entity. Reports on autologous stem cell transplantation (ASCT) in this group are only occasional. Sixty-four patients with T and null cell ALCL from 25 European centres had been registered with the European Group for Blood and Marrow Transplantation (EBMT) at the onset of this study. The median age was 25 years (range 3.2-53.0). Thirty of the 64 patients (47%) were in complete remission (CR), 18 (28%) in partial remission (PR), and the remaining 16 (25%) had a more advanced or chemotherapy-refractory disease at transplant. Eighty-one percent of the patients were conditioned with chemotherapy alone and 75% received marrow stem cells. All the patients transplanted in first CR (15), except one, maintained the CR over time; six of 15 transplanted in CR subsequent to first, six of 18 transplanted in PR and 14 of 16 transplanted in refractory or relapsed disease progressed. Actuarial overall survival (OS) at 10 years is 70%. Multivariate analysis showed that good status at transplant, younger age, absence of B symptoms and absence of extranodal disease indicated a better prognosis. These data suggest that ASCT should be considered as a possible treatment for chemosensitive patients in CR or PR. However, definitive conclusions cannot be drawn from this study and a prospective randomised trial between ASCT and conventional chemotherapy may be indicated.