A 41-year-old woman died within a few hours one morning due to massive rectal hemorrhage. At autopsy, complete liver cirrhosis, signs of portal hypertension, liquid blood in the entire colon, and high-grade anemia were detected. The source of bleeding was a ruptured submucosal varix in the sigmoid colon, which was almost invisible even microscopically and had been caused by portal hypertension. In the vicinity, and somewhat further away from the rupture site, numerous, greatly dilated veins with wall sclerosis and intimal thickening, as well as paravascular iron deposits, were found as indications that severe hemorrhages had already occurred earlier. To detect the source of bleeding, meticulous inspection and dissection with hematoxylin and eosin, elastica van Gieson, and iron staining, were necessary.