Polyposis syndromes require special attention because of benign and malignant complications. Polyposis syndromes account for fewer than 1% of newly diagnosed colorectal cancers. The risk for extracolonic cancers is increased in most polyposis syndromes. Classification relies on the histologic type of polyp (adenomas, hamartomas, hyperplastic polyps), patient age at diagnosis, distribution within the gastrointestinal tract, polyp count, and extraintestinal features. Multiple adenomas (>10) are suspicious for underlying familial adenomatous polyposis, attenuated adenomatous polyposis, or MYH-associated polyposis (MAP). Hamartomatous polyposis syndromes include Peutz-Jeghers syndrome and familial juvenile polyposis. All syndromes except MAP are inherited with an autosomal dominant trait. This implies that first-degree relatives (parents, siblings, offspring) have a 50% risk of carrying the underlying germline mutation as well. Contacting a familial colorectal cancer center is advised in any uncertain cases. Polyposis syndromes are an important risk factor for small bowel cancer. We therefore review this rare but important neoplasm.