Abstract: Abstract:Objective To investigate the expressions and clinical significance of zeta-associated protein 70 (ZAP70) gene in adult patients with acute lymphoblastic leukemia(ALL). Methods Expressions of ZAP70 were detected by real-time fluorescent quantitative polymerase chain reaction (RQ-PCR) in 73 de novo adult ALL patients to analysis the relationship between its expressions and clinical effectiveness. Results The correlation co-efficiencies were over 0.998 for standard curves of RQ-PCR method. ZAP70 expressions were detected in 69.8% ALL patients. There were no statistical differences of ZAP70 gene expression levels in FAB subgroups.However, ZAP70 gene expression levels of T-ALL patients were significantly higher than that of B-ALL and biphenotypic ALL (P<0.01) in immunophenotyping groups. The expressions level of ZAP70 gene were not correlated to peripheral white blood cell (WBC) counts， hemoglobin level, platelet counts and percentage of bone marrow blast cell at presentation. Statistical analyses showed that the difference of complete remission (CR) rates between high and low ZAP70 expressions in de novo ALL patients was not significant (P>0.05).In common B-ALL subgroup,the CR in the group with high expression level of ZAP70(52.6%)was significantly lower than that in the group with low expression level of ZAP70 (85%)(P＝0.041). Patients with high expression levels of ZAP70(48.3% vs. 21.7%,P＝0.048）. Conclusion High expression of ZAP70 might be regarded as an important risk factor in ALL,which predicts a poor prognosis.