By cranial sonography through the open fontanelles of infants with hydrocephalus a diagnosis of position and function of ventricular shunts is possible. A malposition of the ventricular catheter was diagnosed sonographically in 11 of 55 patients after primary shunting. Complications after shunting as overdrainage or shunt insufficiency could be demonstrated early and reliable. Controls in due course are diagnostically important. The number of computerized tomographies in infants with hydrocephalus can be reduced significantly. In order to reduce complications after shunting an intraoperative sonographical control of catheter position is intended.