To compare and characterize retrospectively the clinicopathologic features of gastric cancers with and without previousHelicobacter pyloriinfection, we determined the preoperative seropositivity ofH. pyloriin 151 patients who had undergone gastric resection for primary gastric adenocarcinoma between 1988 and 1993. The overall seroprevalence ofH. pyloriwas 60.9%.H. pylori-positive gastric cancers were frequently associated (p < 0.05) with macroscopic localized types (Borrmann I and II) in which negative cancer associated with infiltrative types (Borrmann III and IV) and cancer invasion of the duodenum. Multivariate analysis showed thatH. pyloriseropositivity was not an independent prognostic factor. Pathologic tumor–node–metastases (TNM) stage remained the only prognostic indicator. Our study suggests thatH. pylorihas a significant impact on the clinically relevant tumor biology of gastric cancer. Investigation along this line is warranted.