Serrated polyps of the colorectum are heterogeneous lesions, a subset of which is now regarded as the precursor of colorectal cancer with DNA microsatellite instability. The serrated pathway encompassing hyperplastic aberrant crypt foci, hyperplastic polyps, sessile serrated polyps (adenomas), mixed polyps, and traditional serrated adenomas, with a meticulous review of their up-to-date histological classifications, is presented. Some remarks concerning genetics of serrated polyps and the mechanism leading to carcinoma development are also included.