Abstract: Previously, we have reported a colorimetric method for the determination of three sapogenins of Panax gensing root. This paper deals with the quantitative determination of both the total saponin and three groups o~ saponins in Panax gensing root by Thin layer chromatography and subsequent reaction with vanillin-perchloric acid reagent. The method has been applied to the comparison of various samples, including those from different sources, of different years of growth and different parts of the root. It has also been successfully applied to the assay of callus cultures of Panax gensing. The proposed procedure is as follows.Weigh accurately 1 g of pulverized 40 mesh sample. Macerate with 25 ml MeOH over night and reflux on a water bath for 6 hours. Take an aliquot of 5 (10) ml of the extract, evaporate, and dissolve the residue in 1(2) ml MeOH, Spot 10～20μl of the prepared sample solution on a silicagel G plate, then develop with a mixture of chloroform-methanol-water, 70:55:10 and 60:42:11 for total saponin and three groups of saponins respectively. The spots are located by iodine vapor, and scrapped into 10 ml glass stoppered test tubes. Add accurately 0.2 ml of 5% vanillin-acetic acid solution and 0.8 ml of HGlO₄. Warm the mixture at 60℃ for 15'. Add 5 ml of glacial acetic acid. Mix the solution well, cool to room temperature. Centrifuge, and take the supernatant solution for colorimetry at 560 nm against a reagent blank.