Postoperative ileus has been thought to be related to intraoperative manipulation of the intestines and to the duration of operative procedures. In order to study the effect of these variables on the postoperative myoelectrical activity of the intestine, six stumptailed monkeys had strain-gauge force transducers and bipolar electrodes placed on gastric antrum, mid-small bowel, right colon, and sigmoid colon. The animals were then subjected to three operations in random order varying in extent and site of dissection: (1) midline incisions, mobilization of right colon and kidney, clamping of renal pedicle, and extensive blunt dissection of right retroperitoneum; (2) the same operation but done on the left side; and (3) midline incision and gentle digital manipulation of the intestines. The first two procedures involved much more intestinal handling and dissection and took five to six times longer than the minimal laparotomy procedure. Postoperative inhibition of bowel motility was most profound and persistent in the colon. The duration and pattern of postoperative ileus in these experiments were independent of the extent, site, and duration of the operative procedure.