Ninety-one patients with de novo acute myeloid leukemia (AML) in first complete remission (CR) undergoing an HLA-identical sibling BMT and with a minimum follow-up of 12 months were analyzed for disease-related and transplant-related variables predicting survival and relapse. The overall actuarial 5 year survival is 53% and the relapse rate 29%, with a medium follow-up for surviving patients of 1552 days (range 365-4094 days). In univariate analysis the following variables were found to be associated with an increased risk of failure: high-dose cyclosporin (CsA), M4-M6 FAB subtype and a long interval (> or = 180 days) between diagnosis and BMT. Other disease-related variables at presentation were not significant, including WBC count > 50 x 10(9)/l, marrow blasts < 70%, time to enter remission > 40 days and > 2 courses to enter remission. Survival was 58% vs 43% for M1-M3 vs M4-M6 FAB subtypes (p = 0.03) and 71% vs 42% for low-dose vs high-dose CsA (p = 0.01). A multivariate analysis was then run separately on survival, relapse and transplant related mortality (TRM). Survival was negatively influenced by M4-M6 FAB subtypes (p = 0.009), high-dose CsA (p = 0.03) and a long interval between diagnosis and BMT (p = 0.04). Leukemia relapse was higher in patients receiving high-dose CsA (p = 0.003) and in females (p = 0.04). Transplant-related mortality was higher in FAB M4-M6 patients (p = 0.01) and patients grafted late after diagnosis (p = 0.03).(ABSTRACT TRUNCATED AT 250 WORDS)