31 colonic polyps in 21 patients between 2 and 30 years of age removed by endoscopy were studied. The site, size, cytohistological characteristic and tissue CEA content of these polyps were evaluated. 58% of the polyps were located in the rectum and sigmoid, the remaining 42% were in the descending colon. At histological examination 13 polyps proved to be neoplastic, 3 of which had severe dysplasia. In 3 cases of juvenile hyperplastic hamartomatous polyps and in 5 cases of inflammatory polyps the tissue C.E.A. was low; in 13 neoplastic polyps it was in direct correlation with the degree of dysplasia. Moreover in 10 patients with neoplastic polyps, 5 presented further adenomas at follow-up, and in 3 of them the C.E.A. tissue content of the first polyps obtained was medium to high. The occurrence in young patients of polyps of the colon with C.E.A. content medium to high must be followed by endoscopic examination at close intervals.