Anisakiasis refers to the infestation of humans by a species of marine nematode larvae belonging to the subfamily Anisakidae, and this condition is seen in people who eat inadequately prepared or raw salt-water fish and squid. Because Koreans like to eat raw fish, anisakiasis of the stomach has been reported occasionally, but involvement of the small bowel or colon is relatively rare. In the case of the colon, anisakiasis of the ascending colon or the transverse colon has been only infrequently reported, and the incidence of rectal anisakiasis is very rare. The present case is a 58-year-old man with no definite abdominal symptoms who visited our hospital for a medical checkup. A 2 cm sized whitish linear live larva was revealed in the rectum and it was removed by colonoscopy. (Korean J Gastrointest Endosc 2006;32:156159)