Progress has been made in understanding BCR-ABL-positive leukemias. A new transcript (p230BCR-ABL) has been characterized that is associated with Ph-positive chronic neutrophilic leukemia. The ATM protein appears to be a regulator of ABL activity in response to irradiation damage. Pathways linking BCR-ABL to the BCL-2 family of proteins may be active in Philadelphia-positive cells and inhibit apoptosis. The 62-kD protein constitutively phosphorylated in chronic myeloid leukemia progenitors has been cloned. Ph-negative long-term culture-initiating cells are detectable in many chronic myeloid leukemia patients. The combination of interferon alfa and cytarabine appears to be superior to interferon alfa alone. Autografting with in vivo-purged stem cells may induce prolonged remissions. Specific inhibitors of the BCR-ABL tyrosine kinase are becoming available.