In this study,the colonization and distribution of Helicobacter pylori (Hp) in patients with chronic gastric diseases were investigated and the relationship between the periodontal initial treatment and presence of Hp in oral cavity was examined to better understand the connection between Hp infection and chronic diseases.Primers for PCR amplification were designed according to ureC gene and cagA genes of Hp.Specimens were harvested from different sites of 96 patients with chronic gastric diseases and the specimens of dental plaques,gargles and dorsal mucosa were tested for Hp.The 96 patients were treated by bismuth triple therapy and among them,52 subjects were additionally given periodontal initial therapy.The eradication rate of gastric Hp and oral Hp detection rate were determined 4 weeks and 1 year after the treatment.The results showed that the detection rates of oral specimens were in the order of dental plaques (82.3％),gargles (51.1％) and scrapings of dorsal mucosa of tongue (37.5％).One year after bismuth triple therapy or the triple therapy in com bination with periodontal initial treatment,the eradication rate of gastric Hp was significantly higher in the combination treatment group than in group treated by the triple therapy alone (62.8％ vs.32.4％,P＜0.05).Moreover,the Hp detection rate was significantly lower in the combination group than in the group treated only with the triple therapy.We are led to conclude that Hp is present at various parts of oral cavity,oral Hp might be an important source of gastric Hp and the triple therapy plus periodontal initial treatment can enhance the long-term eradication rate of gastric Hp in patient with both chronic gastric diseases and chronic periodontitis.