OBSTRUCTION of the duodenum occurring in infants and children is almost invariably the result of congenital maldevelopment. The origin of the obstruction may be intrinsic or extrinsic. Intrinsic obstruction is usually caused by atresia and is therefore complete. However, incomplete intrinsic obstruction due to stenosis may also occur. Extrinsic obstruction is usually incomplete and is frequently accompanied by other anomalies. These accompanying anomalies may be malrotation of the colon, midgut volvulus, or both. Abnormalities in the second stage of intestinal rotation may account for the extrinsic duodenal obstruction, the malrotation of the colon, and the midgut volvulus. The embryologic aspects of the conditions resulting in duodenal obstruction have been thoroughly and completely presented in the publications of Dott,1 Ladd,2 Wakefield and Mayo,3 Gardner and Hart,4 Webb and Wangensteen,5 Haymond and Dragstedt,6 and others. Further elaboration on this phase of the problem would be unnecessarily