We have been using general anesthesia with thoracic epidural anesthesia to manage intrao-perative and postoperative pain for thoracic and cardiac surgery patients. Hemodynamic changes due to sympathetic block with epidural anesthesia is dependent on the level of sympathetic block. Thoracic epidural anesthesia block the cardiac sympathetic innervation, so there may be changes of cardiac function and pressure dependent coronary blood flow especially in coronary artery diseases. To investigate the effects of thoracic epidural anesthesia on coronary blood flow and hemodynamic changes, we performed thoracic epidural anesthesia by injection of 0.5% bupivacaine via a surgieally introduced catheter in dogs. The results were as follows ; 1) Coronary blood flow, systolic, mean and diastolic blood pressure, heart rate and cardiac output were decreased at 5 min, 10 min, 15 min, 20 min, 30 min, 45 min, 60 min, 90 min, 120 min after epidural injection of 0.5% bupivaeaine compared to control value (p<0.05). 2) Systemie vascular resistance, central venous pressure, pulmonary artery pressure, pulmonary capillary wedge pressure, stroke volume and pulmonary vascular resistance were not changed after epidural injection of 0.5% bupivacaine.