Bone marrow transplantation is effective in eradicating leukemia in over 90% of patients with chronic myelogenous leukemia (CML). This efficacy relates to some extent to the antileukemia effect of high-dose chemotherapy and radiation. An immune-mediated antileukemia effect of graft-versus-host disease is also important. In CML, a novel T-cell-mediated mechanism of leukemia eradication is also probably active. In this article we describe this novel mechanism, present preliminary data to support the notion and suggest that it might be exploited to treat CML in a context other than bone marrow transplantation.