Postoperative radiographic findings in the gastrointestinal tract were analyzed in 43 of 72 patients with gastric bypass for morbid obesity. In 15 patients studied because of early postoperative vomiting or abdominal pain, two showed leak from the proximal gastric pouch and six showed impairment of proximal pouch emptying at the anastomosis or proximal efferent loop. In four of the six, the impaired emptying was due to transient postoperative edema and improved spontaneously. Three patients had impairment of distal gastric pouch emptying due to pylorospasm. Five patients studied in the late postoperative period showed dehiscence of the gastric staple line, which can be difficult to demonstrate radiographically. Familiarity with the normal and the abnormal radiographic appearance after gastric bypass is important in elucidating the nature of the problems that can arise after this operation.