A plea is made for greater precision in the use of the word "polyp," which has, unfortunately, become increasingly used as synonymous with "adenoma." There are many different pathological varieties of benign intestinal polyp. The classification here presented emphasizes that the only precancerous polyps are the adenoma, papillary adenoma, and villous papilloma. The distinction between the different histological types of intestinal polyp is discussed with particular reference to adenomas of the colon and rectum in children and young adults and the hamartomatous group of polyps including the Peutz-Jeghers and juvenile types. The pathology of carcinoma in association with ulcerative colitis is described and an explanation offered for these unusual pathological appearances. The value of a careful follow-up of every patient with ulcerative colitis for an indefinite period of time is emphasized.