Of 97 children operated on for duodenal obstruction, lesions extrinsic to the bowel lumen were responsible for symptoms in 64, while the remaining 33 children had intrinsic obstruction. Duodenal atresia was the most common of three lesions causing intrinsic obstruction, while the most frequent causes of extrinsic duodenal obstruction were congenital peritoneal bands and compression by an overlying superior mesenteric artery. Hematoma, annular pancreas, or duplication were seen in the remaining children with extrinsic obstruction. Diagnosis was established preoperatively in nearly all cases by plain or contrast abdominal roentgenograms. Nine children required a second operation, because the site of obstruction was not identified at the first procedure. Extensive duodenal mobilization in patients with either type of obstruction facilitates both identification of the point of obstruction as well as construction of bypass anastomosis, if necessary.