Twenty-four patients with acute non-lymphoblastic leukemia (ANL) in second remission were transplanted from HLA-matched siblings. Twelve patients died of non-leukemic causes and four of recurrent leukemia. One patient is alive after relapse and seven patients are alive and free of disease 114-1907 days after transplantation. The first seven patients received 1000 rad total body irradiation (TBI) in a single exposure. The last 17 were entered on a randomized study to receive 1000 rad TBI as a single dose (seven patients) or 1200 rad TBI fractionated over six days (10 patients). Only one of the 10 patients receiving the fractionated TBI is alive and free of disease 786 days after transplantation while three of the seven receiving single-dose TBI remain in remission 114-541 days after grafting. Even if larger numbers of patients were accrued to this study, it is unlikely that the use of fractionated TBI would prove superior to single-exposure TBI. The actuarial analysis showed that the relapse rate for all 24 patients transplanted in second remission was 50% which was equivalent to patients with ANL transplanted in relapse. The disease-free survival two years after transplant was 24% for patients transplanted in second remission as compared to 26% for patients transplanted in relapse.