The ability of military anti-shock trousers (MAST) to increase central venous pressure and improve cardiac filling pressure suggests that they might be useful in the prehospital treatment of pericardial tamponade. This study utilizes a canine model to examine the hemodynamic effects of MAST inflation on experimentally induced pericardial tamponade. Use of the MAST garment improved cardiac filling, mean arterial pressure, and cardiac output in the decompensated tamponade state. It should be realized that animal data may not correlate with human clinical response.