OBJECTIVES: I. Compare unrelated donor bone marrow transplantation using T-cell-depleted marrow versus unmodified marrow in adults and children with leukemia. II. Evaluate 2-year leukemia-free survival, primary and secondary graft failure, graft-versus-host disease, infection, and relapse in these patients. III. Assess the quality of life associated with T-cell-depleted versus unmodified, unrelated donor transplantation.