AIM:To determine the prevalence of Helicobacter pylori(H.pylon)infection,the serum anti-H,pylori immunoglobulinG(IgG)and IgA antibody responses,and the value of clinicalpresentations in diagnosis of H.pyloriinfection in patientswith gastric atrophy,intestinal metaplasia and dysplasia.METHODS:Ho pyloriinfection was detected by histology in209 patients with mild chronic atrophic gastritis(CAG,n=76),severe CAG(n=22),mild intestinal metaplasia(IM,n=22),severe IM(n=58),or dysplasia(DYS,n=31).Serum anti-H.pylori IgG and IgA were double sampled and evaluatedby enzyme-linked immunoadsordent assays.35 clinicalpresentations were observed and their relationship with H.pyloriinfection was analyzed by the k-means cluster method.RESULTS:Both IgG and IgA levels in H.pylori positivepatients were significantly higher than those negative for H.pylori(P<0.001-0.01).The prevalence of H.pyloriwas highestin severe IM(84.5 %),and lowest in mild CAG(51.3 %)(P<0.01).They were similar in severe CAG(68.2 %),mildIM(72.7 %),and DYS(67.7 %).In H.pylonpositive patients,the IgG levels in severe CAG were significantly higher thanthose in mild CAG(P<0.01).In H.pylorinegative patients,both IgG and IgA levels increased remarkably in severe IM,compared to those in mild IM(P<0.01-0.05).H.pyloriinfectionexhibited no association with patient’s gender(62.1%inmales;71.7%in females)and age(r=0.0814,P=0.241).The diagnostic accuracy based on 35 clinical presentationswas 65.7 %.It could be improved by 5.7%when only theassemblage of digestive symptoms were engaged,or by8.6%when the pathogenic factors,general status andgrossoscopy were combined.The diagnostic accuracy couldbe decreased when only the general symptoms wereengaged,or when the pathogenic factors were accompaniedwith some common digestive symptoms.CONCLUSION:H.pyloriinfection is a major risk factor forthe process from atrophy,IM to DYS of gastric mucosa.Serum IgG and IgA are good indicators to evaluate this progress with a certain arrearage.Investigation on theeffective assemblages of clinical presentations may providea better understanding in the pathogenesis,diagnosis andtreatment for H.pylori infection. AIM: To determine the prevalence of Helicobacter pylori (H. pylon) infection, the serum anti-H, pylori immunoglobulin G (IgG) and IgA antibody responses, and the value of clinical presentation in diagnosis of H. pylori infection in patients with gastric atrophy, intestinal metaplasia and dysplasia. METHODS: Ho pylori infection was detected by histology in209 patients with mild chronic atrophic gastritis (CAG, n = 76), severe CAG (n = 22), mild intestinal metaplasia (IM, 58), or dysplasia (DYS, n = 31) .Serum anti-H.pylori IgG and IgA were double sampled and evaluatedby enzyme-linked immunoadsordent assays.35 clinicalpresentations were observed and their relationship with H.pylori infection was analyzed by the k- means cluster method. RESULTS: Both IgG and IgA levels in H. pylori positive patients were significantly higher than those negative for H. pylori (P <0.001-0.01). The prevalence of H. pylori was highest in severe IM (84.5%), and lowest in mild CAG (51.3%) (P <0.01). They were similar in severe CAG (68.2%), mild In H. pylon positive patients, the IgG levels in severe CAG were significantly higher thanthose in mild CAG (P <0.01). In H. pylorine gative patients, both IgG and IgA levels increased remarkably in severe IM, compared to those in mild IM (P <0.01-0.05) .H.pylori infectionexhibited no association with patient’s gender (62.1% in males; 71.7% in females) and age (r = 0.0814, P = 0.241) Diagnostic accuracy based on 35 clinical presentations was 65.7%. It could be improved by 5.7% when only theassemblage of digestive symptoms were engaged, or by 8.6% when the pathogenic factors, general status andgrossoscopy were combined. The diagnostic accuracy could be decreased when only the general symptoms wereengaged, or when the pathogenic factors were accompanied with some common digestive symptoms. CONCLUSION: H. pylori infection is a major risk factor forthe process from atrophy, IM to DYS of gastric mucosa. Serum IgG and IgA are good indicators to evaluate this progress with a certain arrearage.Investigation on theeffective assemblages of clinical presentations may providea better understanding in the pathogenesis, diagnosis and treatment for H.pylori infection.