Objective: To identify aberrant gene expression in primary human T-cell acute lymphoblastic leukemia (T-ALL) and to evaluate the differently expressed level of Lyl1 and LMO2 genes in human LMO2 positive/TAL1 negative T-ALL tumors.Methods: Three methods, representational difference analysis (RDA) of cDNA, cDNA microarrays and RT-PCR were used to detect if Lyl1 and LMO2 genes were differently expressed in human LMO2 positive/tal1 negative T-ALL tumors.Results: The results of cDNA RDA and cDNA array shown that Lyl1 and LMO2 genes are differently expressed in human T-cell tumors. The result of RT-PCR also shown Lyl1 and LMO2 are high expressed in human T-cell tumors and very low level or no expressed in normal group. Conclusion: We have found that cDNA RDA and cDNA microarray can be successfully used to identify aberrant gene expression in T-ALL cells. In the study described in this manuscript we found that Lyl1 and LMO2 are aberrantly expressed in human T-ALL LMO2 positive/TAL1 negative T-ALL tumors.