There are 3 systems currently in use for diversions of CSF from the lateral cerebral ventricles into the cardiac atrium. All systems have the following similarities: 1. One or more unidirectional valves to prevent reflux of blood into the system. 2. A flushing device for clinical evaluation of patency. 3. Insertion by a simple surgical procedure requiring a single surgical team. 4. Prevention of fluid and electrolyte loss. The major complications of obstruction, infection and thromboembolism frequently produce roentgenographically detectable manifestations. A sequential approach and roentgenographic check list will aid greatly in accurate diagnosis.