The aim of the study was to assess (1) the prevalence of colon related symptoms among the elderly and (2) whether different definitions identify different subjects with Irritable Bowel Syndrome. The study was carried out in a random sample of 1119 70-year-old Danes of whom 72% answered a questionnaire concerning colon related symptoms. The number of bowel movements a week ranged from 0 to 21 among men and 1 to 28 among women, 5% limits were at 15 movements a week. The individual symptoms occurred with prevalences between 16 and 25% among men and 27 and 41% among the women. Abdominal pain, distension and borborygmi occurred significantly more often among women than men, whereas no sex difference was found for alternating stool consistency and number of bowel movements. According to the different definitions the prevalence of Irritable Bowel Syndrome varied from 0 to 18% among men and 4 to 32% among women. The subpopulations with Irritable Bowel Syndrome identified by various definitions had less than half of the subjects in common.