Patients infected with Helicobacter pylori, a stomach colonizing bacteria, have an increased risk of developing gastric malignancies, in particular gastric carcinomas. This review was aimed to analyze the relationship between gastric carcinoma and Helicobacter pylori infection and to rule out the possibility of preventive measures. To identify articles for this review, a PubMed search was conducted using the following key words: gastric cancer, Helicobacter pylori. The risk for developing cancer includes environmental, host-genetic and bacterial factors, which induce physiologic and histologic changes in the stomach. There are two major pathways for the development of gastric cancer by helicobacter pylori: the indirect action on gastric epithelial cells through inflammation leading to gastric atrophy and intestinal metaplasia and the direct action through the induction of protein modulation and gene mutation.