Length, diameter and surface area of each of 6 segments of the large intestine were determined and calculated in 920 Japanese patients who underwent barium enema. Of the length and surface area measurements obtained, those of the transverse colon were the largest, followed by those of the sigmoid colon. The diameter of the ascending colon was the largest, while those of the descending colon and sigmoid colon were the smallest. There were various sex differences in size of the large intestine. Length and surface area of the entire large intestine in males were shorter and smaller respectively than those in females. Lengths of the cecum, ascending colon, transverse colon and rectum in males were shorter than those in females. Diameters of the descending colon, sigmoid colon and rectum in males were larger than those in females. Total surface areas of the ascending colon and transverse colon in males were smaller than those in females, while total surface areas of the descending colon, sigmoid colon and rectum in males were larger than those in females. Length of the entire large intestine tended to be increased with age. Length and surface area of the entire large intestine tended to be increased with an increase in physical dimensions in females.