This paper reports the results of quantitative examination of bifidobacteria and identification of pathogenic bacteria from feces of 100 cases of infantile diarrhea in Chongqing. The logarithmic value of bifidobacteria in one gram of feces is 1.83
significantly different from the normal value in the same age groups (10.5+0.93). The and-infectivc mechanism of bifidobacteria and significance of preventing infantile diarrhea with bifidobacteria biologicals were discussed