A hyperplastic polyp is the most common non-neoplastic polyp in the colon and the rectum. It has been considered as an innocuous lesion and claimed to have a significant relation with carcinomas. There have been reported two types of polyps: multiple hyperplastic polyps (hyperplastic polyposis) and large hyperplastic polyps. The large hyperplastic polyps are bigger than 1 cm. Although both hyperplastic polyposis and large hyperplastic polyps are rare, but recently, we experienced two cases of hyperplastic polyposis. One patient showed numerous diminutive sessile lesions, a large pedunculated polyp and a large juvenile one. One of hyperplastic polyps showed an adenomatous change. The other patient showed numerous sessile lesions associated with several adenomatous polyps, one of which contained a mucosal carcinoma. Hyperplastic polyposis should be defined and differentiated from familial adenomatous polyposis. (Kor J Gastroenterol 1999;34:693 - 697)