Chronic myelogenous leukemia (CML) is a chronic myeloproliferative disorder with an initially chronic course lasting for 3–5 years. It eventually transforms into accelerated and blastic phases, which are generally fatal. CML was one of the first diseases in which a specific chromosomal abnormality was identified, a t(9;22)(q34;q11) or Philadelphia chromosome. CML had been traditionally treated with conventional chemotherapy with hydroxyurea or busulfan. Although these agents can achieve hematologic remissions in most patients, no evidence of sustained disappearance of the chromosomal abnormality was evident. Interferon alpha (IFN-α) has been able to achieve hematologic and cytogenetic remissions in a significant number of patients, and recent studies show a survival advantage for patients treated with IFN-α compared with those treated with conventional chemotherapy. The results of these studies are discussed, and the reasons for discordance among different investigators analyzed in this review. Allogeneic bone marrow transplantation (BMT) may be curative in some patients with CML. The benefits and limitations of this approach in the treatment of CML are also discussed and the results of different alternatives compared. Other alternatives of therapy, including newer chemotherapeutic agents, combinations of IFN-α with other agents, and autologous BMT, are presented. The availability of very sensitive techniques for detection of the Philadelphia chromosome at the molecular level has allowed the detection of minimal residual disease. The information available on these measurements is also analyzed. Finally, we discuss the alternatives for patients with accelerated and blastic phase CML, as well as the clinical characteristics and prognosis for patients with Philadelphia-chromosome-negative