The widespread use of central venous catheters in the treatment of pediatric patients has caused an increased incidence of complications. A rare, but potentially fatal complication occurs when the heart is perforated by the catheter tip causing a cardiac tamponade. This perforation of the heart generally is associated with the insertion procedure, but may also occur after some time because of displacement of the catheter tip. The authors present three cases in which the placement of a central venous catheter resulted in lethal cardiac tamponade. Proper positioning of the catheter tip in the superior vena cava and a high index of suspicion are essential in preventing this serious complication. Contrast-enhanced chest x-ray after insertion of the catheter must be performed to ascertain a correct position of the tip.