Pantothenic acid and biotin contents in Panax Ginseng roots were determined microbiologically with L. arabinosus 17-5. Detection of the vitamins was achieved by the thin-layer chromatography and PPC. Pantothenic acid and biotin were found at the Rf values of 0.42 and 0.55 respectively on the thin-layer chromatograms. In order to find out whether or not the L. arabinosus growth promoting factors contained in the respective ginseng extracts, as shown by the microbiological assay, were really the vitamins respectively, PPC was carried out. Microbiological assay of the vitamins met with results that the average pantothenic acid content in the roots was 6.6r/g, calculated as Ca-pantothenate, and the average biotin content 9.24 mr/g.