Data on 405 patients with chronic myelogenous leukemia who received bone marrow transplants in chronic phase were analyzed for factors predictive of outcome. The 4-year actuarial probability of relapse was 19% (95% confidence interval [Cl], 12% to 28%) and of survival, 55% (95% Cl, 50% to 60%). In multivariate analyses the probability of relapse was higher for recipients of T-cell-depleted bone marrow compared with recipients of non-T-cell-depleted bone marrow (relative risk, 5.4; P < 0.0001) and for patients who did not develop chronic graft-versus-host disease with patients who did (relative risk, 3.1; P < 0.01). The probability of survival was lower for patients who developed moderate to severe acute graft-versus-host disease than for patients with no or mild acute graft-versus-host disease (relative risk, 3.7; P < 0.0001), and in patients aged 20 or older than in younger patients (relative risk, 2.6; P < 0.0002). Duration of disease before transplant was not associated with outcome. Bone marrow transplantation done in the chronic phase of chronic myelogenous leukemia offers some patients prolonged leukemia-free survival. The T-cell-depleted grafts are associated with an increased probability of relapse.