Two children who had surgery for pyloric stenosis are presented. Each had an unusual density discovered on an abdominal plain radiograph taken at least a year after surgery for pyloric stenosis. Subsequent investigation showed that this density represented barium from the preoperative contrast studies that had apparently leaked into the soft tissues at the time of surgery but was not recognized at that time. This unusual complication has not been previously reported but could potentially be fairly common. Unnecessary diagnostic testing could be avoided by recognition that this complication does occur.