Colorectal cancer (CRC) is one of the most frequent neoplasms in developed countries and up to 5% of all cases occur in the context of a hereditary syndrome. These hereditary forms often require a high index of suspicion for their diagnosis and specific and specialized management. Moreover, a diagnosis of hereditary CRC has major consequences not only for the patient--for whom there are highly effective preventive measures--but also for the patient's relatives, who may carry the same condition. The most significant advances in the field of hereditary CRC have been produced in the diagnosis and characterization of Lynch's syndrome and serrated polyposis syndrome.