Colonic leiomyoma is a rare condition that accounts for 3% of all gastrointestinal leiomyomas. Many colonic leiomyomas are found incidentally and are sometimes confused with epithelial neoplasms. Most leiomyomas are removed surgically. However, a small peduculated leiomyoma can be removed endoscopically as it has the appearance of an adenomatous polyp. A 54 year-old man underwent a colonoscopic examination due to frequent loose stools. Colonoscopy demonstrated the presence of a small reddish polyp with a short stalk in the sigmoid colon. We performed a successful polypectomy by the use of colonoscopic snare electrocauterization. A pathological examination revealed the presence of a leiomyoma originating in the muscularis mucosa. We report a case of a small peduculated leiomyoma that was removed endoscopically, with a review of the literature. (Korean J Gastrointest Endosc 2008;37:218-221)