E. coli and B. hominis are usually accepted as members of normal intestinal flora during stool examinations, but in recent years there has been controversy as to whether they may be pathogen protozoa. In this study, 92 individuals who were found to have E. coli (58/92) and B. hominis (34/92) in their stools were included in a study of clinical symptoms. No other parasitological or bacteriological agents were found in the stools of these persons. The percentages of intestinal symptoms were found to be 67.2% and 79.4% for E. coli and B. hominis, respectively. As a result of these findings we concluded that intestinal symptoms may be seen frequently if E. coli and B. hominis are present. In conclusion, E. coli and B. hominis may be considered to be pathogens, especially when no other agents are present.