Abstract: Objective :To evaluate the expression of the WT1 gene and its clinical significance inpatients with leukemia. Methods :Expression of WT1 was measured in 78 patients with acute leukemia,among which 10 were patients with CML and 22 were normal controls, using nested RT- PCR. Results :The expression of WT1 increased in 44 of the 60 patients with leukemia, and the positive rate was73.3%. The positive rate for the WT1 gene in acute myeloid leukemia and acute lymphocytic leukemiawas 70.8% and 83.3%, respectively. No significant difference was found between these two groups. TheCR rate was markedly decreased as WT1 gene expression level increased. Short-term follow-up showedthat WT1 gene expression level was markedly decreased after CR, but highly increased after relapse. Conclusion :Monitoring of the WT1 gene by nested RT- PCR would be a useful marker for the detec-tion of minimal residual disease (MRD) in acute leukemia.