It remains controversial whether epithelial dysplasia of the esophagus is a precancerous lesion or not. Forty resected specimens of the esophagus without preoperative irradiation were totally examined to clarify the relationships between dysplasia and squamous cell carcinoma of the esophagus. The entire subserial sections of each esophagus were stained by hematoxylin and eosin for histopathological observations. Diagrams were provided to examine the distribution of dysplasia in the esophagus. Epithelial dysplasia was classified into mild, moderate and severe. Of 32 cases (80%) with dysplasia, 29 (73%) showed mild dysplasia, 23(58%) moderate and 10 (25%) severe dysplasia. The lesions of moderate or severe dysplasia were mainly seen at the mid-esophagus, and this predominant sites were the same as the esophageal cancer. The patients with moderate or severe dysplastic changes were younger than the patients with esophageal cancer. It was possible that moderate or severe dysplasia was closely associated with precancerous lesions.