Seventy-four consecutive patients (median age 31 years) with acute myeloid leukemia (AML) undergoing unpurged autologous bone marrow transplantation (ABMT) in first remission after melphalan and total-body irradiation were studied to assess the impact of 14 modifiable and non-modifiable prognostic factors on relapse and disease-free survival. Thirty patients were alive in continuous CR at a median of 37.5 months (range 3-94), 14 died of transplant-related toxicity at a median of 5.5 months (range 0.5-18), and 30 relapsed at a median of 7.5 months (range 2-23). The actuarial 5-year probabilities of relapse and disease-free survival were 53.4 and 34.2%, respectively. On multivariate analysis, administration of two or more courses of consolidation chemotherapy prior to the harvest and transplant was found to be the most significant factor associated with decreased relapse (relative risk 2.62, P = 0.0012) and improved disease-free survival (relative risk 3.03, P = 0.0009). A nucleated cell dose of > 2 x 10(8)/kg improved disease-free survival (relative risk 2.17, P = 0.045) by decreasing transplant-related mortality (P = 0.047). We conclude that adequate consolidation of remission before ABMT is the most important factor associated with continuing remission after ABMT. Short-term therapy of AML with two courses of consolidation therapy followed by ABMT requires comparison with repeated courses of intensive chemotherapy for efficacy and cost-effectiveness.