An experimental model for myocardial dysfunction has been developed in sheep. Nineteen animals were placed on cardiopulmonary bypass and subjected to 13 to 19 minutes of myocardial ischemia at 37 C. Measurements of cardiac output, stroke volume, and left ventricular stroke work pre and postoperatively, showed that these indices of hemodynamic function were significantly depressed up to one week after ischemic injury. Analysis of Starling curves, confirmed the presence of ischemia induced myocardial depression. Histologic studies demonstrated primarily subendocardial necrosis.