Eighty-five patients (median age 28 years) with acute myeloid leukemia (AML) in first remission underwent allogeneic bone marrow transplantation (BMT) from HLA-identical siblings between 1978 and 1987 after cyclophosphamide and single-fraction total body irradiation with cyclosporine for graft-versus-host disease (GVHD) prophylaxis. The actuarial probabilities of development of acute and chronic GVHD were 57% and 47%, respectively. Twenty-six patients died of transplant-related complications at a median of 3.5 months, and two of unrelated causes. Seventeen patients relapsed at a median of 6.5 months. Forty patients were alive and well at 74-197 months (median 157) after BMT; seven (18%) with limited chronic GVHD requiring therapy. The actuarial 10-year probabilities of transplant-related death, relapse, and disease-free survival were 33%, 25% and 48% respectively. In multivariate analysis, infusion of a lower cell dose, development of GVHD, and age > 35 years were associated with increased transplant-related mortality, donor-recipient ABO incompatibility with a lower relapse rate, and age > 35 years and a lower cell dose with poorer disease-free survival. We conclude that with long-term follow-up, allografting in AML after cyclophosphamide-TBI and cyclosporine has resulted in disease-free survival that is comparable to most currently reported series. Patients who are alive and well 3-4 years after BMT have excellent prospects of long-term survival.