Chronic myelogenous leukemia (CML) is a progressive and often fatal hematopoietic neoplasm characterized by the presence of the Philadelphia chromosome. This arises from a balanced translocation between chromosomes 9 and 22, creating the bcr-abl fusion gene. It is often stated that the only proven curative option is allogeneic stem cell transplantation, which is indicated for only a limited subset of patients. The Bcr-Abl tyrosine kinase inhibitor imatinib represented a major advance over conventional CML therapy. After imatinib treatment, > 90% of patients had a complete hematologic response, and 70%-80% had a complete cytogenetic response. With 5 years of follow-up, the data are very encouraging and exhibit a major change in the natural history of the disease. The understanding of some of the mechanisms of resistance to imatinib has led to a rapid development of new agents that might overcome this resistance. The outlook today for patients with CML is much brighter than that of a few years ago.