Growth responses of some intestinal bacteria such as bifidobacteria and Clostridium perfringens to the extracts of certain foodstuffs were investigated in vitro. Among edible mountain herbs, the extracts of several chui-na-muls (Aster tataricus, Ligularia fischeri and Aster scaber) had an inhibitory activity against C. perfringens on the agar plate and the water extract of Aster scaber worked selectively on it among intestinal bacteria. The water extract showed growth-promoting effect toward bifidobacteria such as B. adolescentis, B. animalis, B. bifidum, B. infantis and B. thermophilum in the broth culture. When the faecal inoculum was incubated in the culture with the extract, the population of C. perfringens decreased, whereas that of bifidobacteria increased by $10^3$ scale.$eta$-glucuronidase activity in the culture with the water extract of Aster scaber digested with pepsin and pancreatin was lower than that in the control culture.