Our hypothesis was that postoperative ileus is caused by the release of neurotransmitters in the gut wall that inhibit motility. We reasoned that blocking the release with octreotide would prevent ileus. We placed serosal electrodes on the small intestine and stomachs of 15 dogs and inserted a duodenal cannula. After the animals recovered, electrical activity was recorded, and small bowel transit, colonic transit, and gastric emptying were studied radiographically and scintigraphically. Ileus was induced by celiotomy and intestinal abrasion. Dogs were randomized to receive on postoperative days 0 through 3 either a placebo (n=5), octreotide, 1.5 μg/kg/8 hr subcutaneously (n=5), or octreotide 0.83 μg/kg/hr intravenously (n=5). Both doses of octreotide resulted in a faster return to preoperative values of small bowel interdigestive myelectric activity and transit and colonic transit than did the placebo. The larger dose of octreotide, however, slowed gastric emptying. In conclusion, octreotide shortened the duration of postoperative ileus in the small bowel and colon of dogs.