To study the expression of RNA editing deaminases ADAR2 and ADAR3 in different malignant glioma cell lines and the effect of phenylacetate on the expression of these genes, the primarily glial cells of human brain tissue were isolated and cultured. The human glioma SHG-44, U-251, BT-325 cell lines were maintained in culture. The expressions of ADAR2 and ADAR3 mRNA were detected by the semiquantitative reverse transcription-polymerase chain reaction(RT-PCR). The changes in ADAR2 mRNA expression before and after phenylacetate treatment were detected by RT-PCR and image analysis. The level of ADAR gene expression is expressed as the ratio expression rate(RER)of ADAR gene to β-actin according to computer image analysis. ADAR2 displays moderate expression in glial cells,low expression in low-grade malignant glioma SHG-44 cells, and high level expression in high-grade malignant glioma U-251and BT-325 cells. The expression of ADAR2 can be decreased by phenylacetate treatment in glioma U-251cells. ADAR3 is not expressed in normal brain glial cells, or glioma SHG-44, U-251 and BT-325 cells before and after phenylacetate treatment. The enhanced expression of ADAR2 may be involved in the tumor progression of malignant glioma. Phenylacetate can decrease the expression of ADAR2 in glioma cells, suggesting that it may act on the RNA editing process in glioma.