Although gastric bypass surgery continues to grow in popularity for dramatic weight loss and considerable weight maintenance in the morbidly obese, there has been little attention given to the possible complications associated with these procedures. It is estimated that more than 10% of patients who undergo the Roux-en-Y procedure have undergone complications; the rate of complications involving the duodenal switch procedure have not been clearly established given that it is still a relatively new procedure. Both an upper GI series and CT examination are important in diagnosing and following up on post-operative complications. Our findings support those of the current literature to include six unusual complications which include the following: internal herniation through the small bowel mesentery, internal herniation through the transverse mesocolon, external herniation through the abdominal wall incision, enterocutaneous fistulas, Roux-en-Y configuration with anti-peristaltic inversion of the gastroenteric Roux limb, and incorrect anastomosis of the Roux limb with the excluded stomach (resulting in a Roux-en-O configuration). In the fluoroscopic evaluation of post-operative gastric bypass patients, a thorough understanding of expected post-operative bowel configuration is essential. In addition to assessing anatomical abnormalities, it is equally important to assess for abnormalities of motility.