A modified method for measurement of pressure activity in the sigmoid colon was presented, using open-ended tubes and measurement of pressure activity for 30 min after i.v. administration of 0.5 mg of neostigmine. The motility index in 12 normal persons had median 597 with a range of 125-1169. Variation among persons exceeded the day-to-day variation significantly. Error in reading the curves was negligible. [This method may be of clinical importance when used in patients with diverticular disease.].