&NA;This study evaluated the ability of two‐dimensional echocardiography (2D echo) to detect and localize the distal end of ventriculoatrial shunt catheters in the cardiac chambers of hydrocephalic patients. Twenty‐eight patients were studied, and the performances of 2D echo and standard chest x‐ray filming were compared. Although standard chest x‐ray filming allowed accurate determination of the catheter position in only half of the patients, 2D echo afforded clear visualization and accurate localization of the catheter in all instances. By its precise definition of intracardiac anatomical landmarks and its excellent time determination, 2D echo can provide valuable information on the movements of the catheter's distal end during the cardiac cycle, during head flexion or rotation, and during deep breathing movements. Some interesting observations were made with 2D echo. A to‐and‐fro motion of the catheter tip through the tricuspid orifice during the cardiac cycle was visualized in two instances. The combination of head movements and deep respiratory movements induced a variation in the position of the catheter tip. The magnitude of this displacement was 6 cm at the most. Two patients underwent reoperation for lengthening or shortening of the catheter. The operative findings confirmed the ultrasonic localization in both cases where the chest x‐ray film had failed to identify or adequately locate the catheter tip. It is concluded that 2D echo is a safe, innocuous, and accurate method with which to locate the distal end of a ventriculoatrial shunt. It is the only available technique that provides visualization of intracardiac structures and cardiac cycle reference. In our neurosurgical unit, 2D echo is now considered the standard reference procedure to localize postoperatively the distal end of ventriculoatrial shunts and to follow patients in an attempt to appreciate the ideal timing for prophylactic lengthening of the shunt. (Neurosurgery14:2‐7, 1984)