Abstract: 　Objective] To establish a method for continuous culture of Entamoeba gingivalis (E.g.) and study the pathogenicity of E.g.. [Methods] The culture conditions of E.g. were compared by observing its growth and reproduction. The pathogenicity of E.g. was studied by investigating its infection rate in humans and observing the relationship between E.g. infection and periodontal abscess in rats and the in vitro effect of some drugs. [Results] The optimal culture condition of E.g. was modified LES medium containing Locke′s solution with 20% bovine serum, penicillin, streptomycin and rice starch. Reproduction of E.g. peaked at the fourth day of incubatoin, E.g. could live continuously for 120 to 168 h. The infection rate of E.g. was higher in patients with periondontal diseases than in healthy groups. The animal test showed that E.g. could cause periondontal abscess in rats. The levels of acid phosphatase and MDA were higher in patients with E.g.-positive periondontal disease than in healthy individuals. Metronidazole and SBF are effective against E.g.. [Conclusion] E.g. could grow very well in modified LES medium, and cause periondontal abscess in patients with low immunity. \;

Key words: Entamoeba gingivalis, culture, animal infection, periodontal abscess.