There are three methods for making chronic myelogenous leukemia (CML) mouse models: xenotransplantation of primary Ph-positive CML cells into immunodeficient mice, BCR/ABL-expressing transgenic mice, and BCR/ABL retroviral bone marrow transduction and transplantation. These animal models have provided us with important new insights into the molecular pathophysiology of CML and answered directly many questions regarding this disease. To date, The model mice using the BCR/ABL retroviral bone marrow transduction and transplantation method has provided the most valuable knowledge compared with the other two methods. After a long history of failure, however, recent studies have reported successful establishment of making the CMLphenotype in transgenic mice. The transgenic CML mouse model now appears to be more accurate, informative and advantageous model for studying CML. This article reviews the history of BCR/ABL-expressing CML mouse models and the recent findings in the transgenic mice with the CML-phenotype.