Between 1978 and 1980 133 patients with acute myelogenous leukaemia were given allogeneic bone-marrow transplants from an HLA-identical sibling and were followed up for at least a year. Pre-transplant preparation consisted of high-dose chemotherapy and/or radiation and post-transplant immune suppression consisted of methotrexate or cyclosporin-A. Data for 76 patients transplanted in first transplanted in either second to fourth remission, partial remission, or relapse. The 2-year actuarial survival-rate was 48% (95% CI, 36-60%) for patients transplanted in first remission and 30% 95% CI, 17-43%) for patients with more advanced disease (p = 0.037). Disease status at the time of transplantation was related to the probability of survival (p less than 0.02). The 2-year actuarial leukaemia recurrence-rate was 32% for patients transplanted in first remission and 50% for patients with more advanced disease (p = 0.0017). The probability of remaining in remission also was associated with disease status at time of transplantation (p less than 0.01). The incidence of graft-vs-host disease and interstitial pneumonitis was similar for patients transplanted in first remission and those transplanted later, and methotrexate and cyclosporin A were equally effective in modifying acute GVHD. These data indicate that prolonged survival can be achieved in approximately one-half of patients with acute myelogenous leukaemia given transplants of bone marrow from an HLA-identical sibling during their first complete remission.