Endoscopic and pathologic examinations were conducted in a randomly chosen population in a high risk area of gastric cancer, Linqu County, Shandong Province. A high prevalence of chronic atrophic gastritis, intestinal metaplasia and dysplasia was found. Gastric mucosal lesions changed from mild to severe with a decline in transition rate. The prevalence rate of severe dysplasia was close to that of gastric cancer. The study indicates that gastric precancerous lesions are related to malignant changes implying that gastric cancer develops on the damaged gastric mucosa. It is also shown that the progression from chronic atrophic gastritis to dysplasia may take an average of 20 years.