Effects of tea polyphenol intake (0.4 g/volunteer, 3 times per day, for four weeks) on fecal microflora, bacterial metabolites, and pH were investigated using eight healthy human volunteers. Counts for Clostridium perfringens and other Clostridium spp. were significantly decreased during the tea polyphenol intake periods. Percentage of volunteers having C. perfringens in their feces decreased significantly, but not for other Clostridium spp. Percentage of Bifidobacterium spp. (the acid forming bacteria) in total counts and the content of volatile fatty acids including acetic and propionic acids increased significantly, which might have reduced the fecal pH. However, the tea polyphenols had no effect on fecal enzyme activities, ammonia, or putrefactive products. Two weeks after discontinuing the intake, the microflora counts and their biological parameters appeared to have returned to normal.