The herbal components should be transformed to bioactive compounds by the intestinal bacteria and then expressed the pharmacological action of herbal medicines. Human fecal enzyme activities related to the metabolism of herbal components were measured. The metabolic activities of puerarin, poncirin, glycyrrhizin, ginsenoside Rb1 and ginsenoside Rb2 to their bioactive compounds were 3.5 +/- 1.18, 333.1 +/-183.64, 95.7 +/- 107.1, 28.6 +/- 10.32 and 20.8 +/- 13.3 micromol/ h/g, respectively. The profile of these metabolic activities of glycyrrhizin and ginsenosides were not changed even if herbal extracts, water extract of Glycyrrhizae Radix and Ginseng Radix, instead of the isolated compounds were used. All the enzyme activities tested were not different between male and female, and between ages. However, the difference of these enzyme activities in individuals was significant. These results suggest that the metabolic activity of herbal components to bioactive compounds may be a factor of constitutional classification, and could be available for constitutional classifications, if the constitutional herbal medicines were used.