Abstract: In a borate buffer medium of pH 9.3,a charge transfer complex with mole ratio of 1 to 1 was formed between aminobutyric acid (ABA) and 2,3-dichloro-5,6-dicyano-benzoquinone (DDBQ) heated at 50 ℃ for 40 min in a water-bath,with its absorption maxima at 340 nm and its molar absorptivity (ε340) of 1.37×103L·mol-1·cm-1.The proposed method has been applied to the analysis of drug tablets for its content of aminobutyric acid,giving RSD′s in the range 1.3% to 1.9%,and recoveries in the range of 98.5%-101.9%.By checking the results obtained by this method with the results obtained by the method of national standard,no significant deviation was observed as proved by the t-test.