This study was purposed to investigate the expression and methylation status of TIG1 in acute leukemia (AL). The TIG1 expression of 53 cases of AL and 20 cases of normal control (NC) were measured by using real-time quantitative PCR (RT-QT-PCR) and methylation-specific PCR(MS-PCR). The leukemia KG-1a, U937 and K562 cells were treated with 5-Aza-CdR. The results indicated that TIG1 gene expressed at a high level in cases of NC, but expressed at a low level in patients with AL. TIG1 gene was unmethylated in NC, but frequently methylated in AL. Aberrant methylation rate of TIG1 in AL was 75% (40/53). The expression of TIG1 in unmethylated patients was higher than that in methylated patients. Hypermethylation of TIG1 promoter CpG islands was detected in all the cell lines. 5-Aza-CdR treatment led to the hypomethylation of TIG1 promoter CpG islands. After the treatment with 5-Aza-CdR of different concentration, the expression of TIG1 was restored, and the effect of 5-Aza-CdR displayed dose-dependency. It is concluded that the reduced expression of TIG1 may play an important role in the pathogenesis of AL, and methylation may be responsible for the decreased transcription of TIG1 gene.