Objective To construct the recombinant rAAV2-hGAD65 vector and detect its function both in vitro and in vivo. Methods The cDNA of human glutamic acid decarboxylase 2 (hGAD65) gene, which was one of gamma-aminobutyric acid (GABA) synthetase, cloned by the method of RT-PCR, was subcloned into the adeno-associated virus (AAV) vector and formed the recombinant vector of AAV-hGAD65 (rAAV2-hGAD65). The recombinant vector was packaged by the AAV Helper-Free System and its titer was detected. The primary fibroblast, cultured from the rat lung, was transfected by the rAAV2-hGAD65. The expression of the hGAD65 in fibroblast was detected by immunohistochemical method and the level of GABA in the media was assayed by high performance liquid chromatograph (HPLC). EM>In vivo/EM>, the hGAD65 was detected by immunohistochemical method in STN and the concentration of the GABA in the reticular part of substantia nigra (SNr) was assayed by HPLC after the rAAV2-hGAD65 was injected into the subthalamic nucleus (STN) by the stereotaxic method. Results The sequence of hGAD65 cDNA was in accordance with that in the Genebank. The amino acid sequence of hGAD65 had no mutation and the titer of rAAV2-hGAD65 was reached 4.5 ×10SUP>11 /SUP>per milliliter. The efficiency of infection to the rat primary firoblasts was 80%, and the concentration of GABA in the media of fibroblasts was (45.66±6.07)nmol/L per liter. EM>In vivo/EM>, hGAD65 could be detected in STN, and the concentrateion of the GABA in the SNr was increased from (5.66±1.07)nmol/g to (12.66±2.59)nmol/g.Conclusion The cDNA of hGAD65 was cloned by RT-PCR and the recombinant vector of rAAV2-hGAD65 was constructed. The AAV can infect the primary fibroblast in vitro and the hGAD65 can catalyse the glutamic acic to GABA. In vivo, the concentration of GABA in the SNr was heighten after the rAAV2-hGA