To evaluate the difference in expressing pharmacological effects of ginseng by intestinal microflora between Koreans, metabolic activities of ginseng, ginsenoside $Rb_1$ and $Rg_1$ by 100 fecal specimens were measured. The ${eta}$-glucosidase activity for p-nitrophenyl-${eta}$-D-glucopyranoside was 0 to 0.42 mmol/min/mg and its average activity (mean${pm}$SD) was $0.10{pm}0.07$ mmol/min/mg. The metabolic activities of ginsenosides Rb1 and Rg1 were 0.01 to 0.42 and 0.01 to 0.38 pmol/min/mg, respectively. Their average activities were $0.25{pm}0.08$ and $0.15{pm}0.09$ pmol/min/mg, respectively. The compound K-forming activities from ginsenoside Rb1 and ginseng extract were 0 to 0.11 and 0 to 0.02 pmol/min/mg, respectively. Their average compound K-forming activities were $0.24{pm}0.09$ pmol/min/ mg and $2.14{pm}3.66$ fmol/min/mg, respectively. These activities all were not different between males and females, or between ages. Although compound K-forming activity from the aqueous extract of ginseng was low compared to that from ginenoside $Rb_1$, their profiles were similar to those of isolated compounds. Based on these findings, we believe that the intestinal bacterial metabolic activities of ginseng components are variable in individuals and may be used as selection markers for responders to ginseng.