Abstract: Aim ：To investigate the expression and the regulation of Bim protein in leukemic cell of patient with chronic myelognous leukemia（CML）. Methods ：The primary leukemic cells from the peripheral blood or bone marrow of patients with CML were isolated and cultured.The expression of Bim in the present or absence of imatinib（BCR/ABL inhibitor） was detected by the Western blotting，immunohistochemical analysis and real-time quantitative PCR. Results ：Bim was consecutively expressed in normal bone marrow，but significantly decreased in the bone marrow of patients with CML（P<0.05).Imatinib significantly enhanced Bim mRNA transcription and expression in the manner of time- and dose-dependence.Moreover，there was reverse correlation between Bim protein level and the percent of leukemic cell in bone marrow（r=0.849 1，P<0.05）. Conclusion ：Bim is the Bcl-2 family pro-apoptitic factor.The decreased expression of Bim could be vital in the CML，Bim protein up-expression following the suppression of BCR/ABL might be of importance in investigation of the Bim-induced apoptosis for potential clinical therapy.