Until very recently, there was general acceptance in the pathology community that all serrated lesions of the colon and rectum without overt cytologic dysplasia were hyperplastic polyps and had no malignant potential. Although there are still several unanswered questions in regard to the relationship between the various serrated lesions, there is a better understanding of the relationship of sessile serrated adenoma to carcinoma. This article discusses hyperplastic polyps, sessile serrated adenoma, traditional serrated adenoma, mixed polyps, and serrated lesions in such conditions as idiopathic inflammatory bowel disease and mechanical trauma. The major focus of the content is on diagnostic features of these lesions.