Intestinal obstruction is no more frequent after gastric bypass than after any other similar gastric surgical procedure. However, occurrence of any complication requiring revisional surgery in these hugely obese patients may have serious implications. Bariatric surgeons and physicians who take part in the care of such patients must be aware of the different clinical pictures which accompany the varying levels of obstruction following gastric bypass surgery. Particularly critical is an understanding of closed loop gastroduodenal obstruction, a potentially lethal complication, which can cause rapidly occurring hypovolemic shock and death within a few hours of onset.