To determine whether an artificial, indwelling, stomal occluding device could provide reliable continence for persons with an ileostomy and a prestomal ileal pouch, the device was tested first in four dogs and then in humans. After initial assessment of pouch volume and pressure-volume relationships in the dogs, the animals underwent progressively longer periods of stomal occlusion with the artificial device, such that 4 weeks later, they were tolerating occlusion for periods of 8 hours. The device achieved complete continence for gas and stool without discomfort in every dog. The pouch capacity rapidly increased, so that infusion of 500 ml of water at 4 weeks elicited less than a 10 cm H2O increase in intrapouch pressure. These encouraging canine results prompted use of this approach in a 55-year-old obese man undergoing proctocolectomy for chronic ulcerative colitis. The device achieved continence in the patient for 4- to 6-hour periods by 2 months after operation without discomfort or adverse sequelae. We concluded that the artificial device rapidly increased pouch capacity and effectively maintained leakproof fecal continence in dogs and humans with an ileostomy and a prestomal ileal pouch.