Objectives: Gastric dysplasia is defined as a lesion characterized by cellular atypia, abnormal differentiation and disorganized architecture without showing malignant nature in histology. Even though it was known as a precursor of gastric cancer, there were few studies in clinical and biological aspect in practice. Because the early detection of gastric cancer is very important, we have evaluated the risk of gastric carcinoma following the gastric dysplasia in prevention of gastric cancer. Methods: The authors evaluated the clinical and histological findings of 27 cases of gastric dysplasia for at least 3-12 months among 38 cases of gastric dysplasia and which confirmed from January 1992 to June 1994. Results: The sex distribution of 38 cases with gastric dysplasia was that men were 29 cases and women were 9 cases. The Highest incidence was above 6th decades(30cases) in age. Twenty seven cases of gastric dysplasia could be followed prospectively. Each histologic findings were as follow, mild dysplasia 12 cases, moderate dysplasia 7 cases and severe dysplasia 8 cases respectively. The endoscopic findings showed erosion 6 cases(16%), flat lesion 8 cases(21%), ulcer 10 cases(26%), polypoid lesion 14 cases(37%) respectively, The evolution of dysplasia was regression 4 cases, persistence 4 cases, progression 3 cases, cancer 1 case(9%) in mild dysplasia and regression 2 cases, persistence 2 cases, progression 1 case, cancer 2 cases(29%) in moderate dysplasia. In eight severe dysplasia, 1 case of regression, 3 cases of persistence and 4 cases of cancer(50%) were developed. Polypectomy was performed in 12 cases and 1 case was regressed from severe dysplasia after mucosal resection. In 27 cases of gastric epithelial dysplasia, gastric cancers were developed in 7 cases(26%) and early gastric cancers were 4 cases(57%) among them and the most common lesion was ulcer(5 cases). Conclusion: Gastric dysplasia should be strictly followed up with repeated endoscopic examination as well as treated the adequate endoscopic procedure for the prevention of progression or the risk of developing cancer.