Pericardial tamponade from an indwelling central venous catheter developed in four orthopaedic patients. Two of these patients died acutely, and the other two sustained severe anoxic brain injury. The early signs of tamponade include tachycardia, hypotension, and increased central venous pressure. The outcome most often is fatal. When a central venous catheter has been placed incorrectly or has migrated, it can perforate the heart and produce pericardial tamponade. To avoid this complication, the tip of the catheter must be placed within the superior vena cava rather than the right atrium, and the position of the catheter must be ascertained with a radiograph of the chest. Prompt recognition and treatment of pericardial tamponade are imperative if a disastrous outcome is to be prevented.