Abstract: A gas chromatographic method for analyzing a-diphenyldicarboxylate, a new drug for hepatitis, is described. The analysis was made on a glass column (1m×3mm) packed with 3% Dexsil 300 on chromosorb W AW (80 to 100 mesh). The temperature was programmed from 200℃ to 270℃ at 10℃ min^-1, and then kept at 270℃ for 5 min. DOP was used as internal standard. Using these conditions, some crude samples and samples for therapeutic use were analysed. It was found that the impurities β-and γ-diphenyldicarboxylate were not present. The coefficient of variation of the determination of three pure isomers α-, β- and γ-diphenyldicarboxylate is 0.63, 0.62 and 1.56% respectively. Samples with different melting points, 158 to 160℃ and 179℃ to 181 have been shown to be identical but of different crystal forms.This method can be used for quality control of this drug.