&NA;Histologic criteria for malignancy in colonic adenomas have been well established, but little has been written regarding the gross or macroscopic appearance of malignant adenomas. The following nine criteria, listed in order of most to least importance, were used to endoscopically evaluate polypoid lesions of the colon: friability, ulceration, firmness, the dunce cap sign, lobulation, asymmetry, size, macroscopic growth pattern, and color. Three cases of the dunce cap adenoma are reported in detail. In evaluating 121 consecutive colonic lesions, 87 percent were resected endoscopically. Eleven carcinomas, three villous adenomas, and two lipomas were not removed via the endoscope.