A retrospective analysis of the endoscopic diagnostic data on 151 cases of gastric polyps of various histological structure was carried out. A relationship between the risk of malignant transformation of gastric polyps, on the one hand, and their histology, presence and degree of dysplasia, on the other, was established. Epithelial dysplasia, in pronounced degree included, was observed in 33.7% of patients with hyperplastic polyps and in all cases of gastric adenoma. Epithelial dysplasia of hyperplastic polyps was mild or moderate in most cases while that of adenomatous polyps was moderate or grave. Gastric cancer as a consequence of malignant transformation of polyps was detected in 15 (9.9%) patients (hyperplastic polyps--2; adenomatous polyps--13). No objective endoscopic criteria for establishing the risk of polyp transformation were developed. Grave epithelial dysplasia, i.e. precancerous lesions in the gastric mucosa, may be suggested as such criterion. Moderate or grave dysplasia of the polyp epithelium should be considered in forming the group at risk first and foremost.