Abstract: A survey of E. gingivalis infestation was conducted in 230 dental patients. The total detection rate was 44.2%. The incidence in the patients with parodontitis and pericoronitis was 60% and 55.8% respectively. But in those with dental caries associated with parodomitis or dental caries alone, E. gingivalis was found only in 27.5% and 14.3% respectively. No significant correlation exists between the detection rate and the age, sex, marriage, occupation or the dietary habits.Observation was also made in 74 normal subjects and the incidence was 32.4%. Significant correlation was found between the rate and the age, marriage and occupation, students being the most affected, probably because they live collectively and share the same dishes at table.This paper discusses whether E. gingivalis is the pathogen of parodontosis. Although a high rate of E. gingivalis infestation was detected in cases of parodontopathy, there is no conclusive evidence to show its pathogenicity.