Recognition of the mendelian dominant inherited syndrome of familial polyposis coli in the 1930s has been followed by the recognition of many inherited colonic polyposis syndromes. The recognition of different histological types of colon polyps was associated by the gradual recognition that some, such as the hamartomatous polyps, do not progress into adenocarcinoma, and others, such as various adenomas have a greater or lesser propensity to eventually give rise to invasive cancer. As the host of inherited syndromes expanded and were more widely recognized, additional inherited characteristics became apparent: such tumors as breast and thyroid associated with Cowden's syndrome, ovarian cysts and sex cord tumors with Peutz-Jeghers syndrome, and, of course, the soft tissue, bony tumors, ampullary cancers, and fibroadenomas associated with Gardner's syndrome. In recent years, genetic markers for the various syndromes have been studied, and in some cases confirmed. This whole field is rapidly developing and is briefly covered. All the steps and influencing factors in cancer development are shown in one phase or another of the polyp-cancer sequence in these inherited syndromes.