The Roux-en-Y anastomosis is a surgical procedure performed to divert the pancreaticobiliary juices from the gastric pouch in patients who have alkaline reflux gastritis or esophagitis, or both, that develop after vagotomy and Billroth I or II operations. After the Roux-en-Y procedure the inflammation subsides but is often replaced by a characteristic group of symptoms--chronic abdominal pain, nausea, and vomiting worsened by eating. Using a semiconductor recording probe, we investigated the Roux limb in 7 subjects who were fasted and then fed (liquid and solid meals). In the fasted state the migrating motor complex was either completely absent or grossly disrupted. Only 1 subject converted to a fed-state motility pattern in the Roux limb after a liquid meal (Osmolite), and all 7 subjects failed to convert to a fed state after a solid meal. These studies suggest that the Roux-en-Y syndrome of pain, nausea, and vomiting is secondary to a defect in motor function and that the Roux limb is acting as an area of functional obstruction.