The use of Teflon in the reconstruction of the stenotic right ventricular outflow tract, such as that associated with the tetralogy of Fallot, has received widespread application. However, it is only within the past year that experimental evaluation of such a prosthesis has been described.1-3 The present experimental study was designed to evaluate the fate of the Teflon patch in rapidly growing myocardium and vessel wall. Method These experiments were performed on a series of 7 pigs, weighing an average of 11.5 kg. The animals were anesthetized with ether, after which a tracheotomy was performed and an endotracheal tube inserted and connected to a positive pressure respirator. The chest was entered through the third intercostal space on the left side. The pericardium was opened anterior to the phrenic nerve. A stay suture was then placed in the right ventricular outflow tract, just proximal to the annulus of the pulmonic