For many years a neoplastic potentiality of the juvenile polyps has been denied. The authors performed a critical review of the international literature about the neoplastic transformation of the juvenile polyps. Each examined case had to respect three conditions: 1) exhaustive hystological findings certifying a clear neoplastic degeneration of a juvenile polyp; 2) clear evidence of single juvenile polyposis (< 5), presence in the colon and rectum only and absence of familiarity; 3) reliable diagnostic practice (endoscopic and/or hystological evidence). During the review we collected 271 cases of juvenile polyposis observed in 12 countries, 97 of which (35.79%) showed neoplastic transformation, adenomatous type in 50 (18.45%) and carcinomatous type in 47 (17.34%), and 13 cases of neoplastic degeneration of single juvenile polyps. The review shows clearly and strongly that the risk of cancer in the juvenile polyposis can reach the risk of the adenomatous polyposis. The neoplastic degeneration exists in the single juvenile polyps even if in a lower degree.