Abstract: Objective: To determine the expression of tumor suppressor in lung cancer 1(TSLC1) in the bone marrow cells(BMC) of patients with acute leukemia(AL),and to evaluate its significance in early diagnosis,prognosis and treatment of AL.Methods: Expression of TSLC1 mRNA in the BMC of 39 AL patients and 10 normal subjects was determined by semi-quantitative reverse transcription polymerase chain reaction(RT-PCR).Results: The positive expression of TSLC1 was 80.00% in the control group,while it was 12.82% in the AL group.The difference was significant(P<0.01).The difference of M1,M2 and M5 in the acute myeloid leukemia(AML) group and the TSLC1 in the control group had statistical significance(P<0.05-P<0.01);the difference of M3 and M4 in AML group and the expression of TSLC1 in the control group showed no statistical significance(P>0.05);the subtype comparison was not statistically different(P>0.05).Conclusions: The loss expression of TSLC1 in AL is a frequent event,which is likely to be correlated with the genesis and progress of AL,and may be of great value in the early diagnosis,prognosis and treatment of AL.