Objective To investigate the expression and its significance of BMI-1 gene in leukemia patients.Methods BMI-1 gene level was assessed by reverse transcription polymerase chain reaction (RT-PCR)in acute leukemia patients,chronic myeloid leukemia(CML)patients,chronic lymphoblastic leukemia(CLL)patients,and bone marrow mononuclear cells(BMMNC)as normal controls,as well as leukemia cell line K562.The expression of BMI-1 gene in leukemia and the relationship was explored.Results The expression of BMI-1 gene was positive in leukemia cell line K562.but negative in 10 controls as well as in CLL.The BMI-1 gene was expressed in 15.4% of CML patients and 47.1% of AL patients.The positive expression of BMI-1 gene in CML-CR was significandy lower than that in CML-BP (P＜0.05).Conclusion BMI-1 gene was over expressed in leukemia patients,and may be related to curative effect of the disease.It may be used for leukemia treatment targeting the provision of new sites.