318 adenomatous polyps were removed by colonoscopic polypectomy, from two hundred patients, between 25 to 88 years old; 60.50% men, and 39.50% women. 86.50% of patients were older than 50 years old. In 64.50% of patients the adenomatous polyp was single, and 35.50% had "multiple adenoma"; the lesions distribution was 72.64% in the rectum-sigmoid colon. The grade of dysplasia was severe in adenomas over 20mm, and in those of villous type. The malignant percentage was: 1.61% in the adenomatous polyp under 10mm in diameter, 8.49% in those of 10mm to 19mm, and 30.68% in the adenomas of 20mm or more. The adenocarcinomatous focus increased from 1.69% in the adenomas under 10mm to 58.33% in those of 40mm or more in diameter. The relationship between type of adenomatous polyp and his adenocarcinoma incidence was 7.66% in tubular type, 22.22% in tubular-villous, and 26.32% in villous type. The carcinoma incidence in all of the adenomas of this series was 11.95%.