1. Objectives This study was aimed to evaluate marker substances in Gamijowi-tang by high performance liquid chromatography(HPLC) 2. Methods The seperation was performed an AquasilC18(4.6X250mm)column by gradient elution with 0.1N H3PO4 in H2O - acetonitrile(0min 100:10,20min60:40, 40min 80:20, 60min 100:0) as the mobile phase at a flow-rate of 1.0 ml/min with detection at 190-800nm 3. Results Ephedrine and schizandrin were established as marker substances in Gamijowi-tang and its qualitative analysis was carried out. Analyzed was similarity of marker substances between in standard article and in Gamijowi-tang. The result of the analysis was that ephedrine and schizadrin showed 0.9999 of similarity, which meant they were really ephedrine and schizadrin. In addition, ephedrin content was 12.16mg, pseudoephedrine conrenr was 5.09mg, and schizandrin content was 26.6mg in 76g of Gamijowi-tang. 4. Conclusions Qualitative and quantitative analyses of ephedrine and schizandrin in Gamijowi-tang were conducted, and it was identified thar they could be used as marker substances in standardizing quality of Gamijowi-rang.