BACKGROUND: There are many documents about the hemodynamic changes according to sympathetic blockade produced by epidural anesthesia, but a few reports have addressed the effects of epidural anesthesia on renal blood flow and function. We evaluated the effects of epidural ane.sthesia on the renal blood flow and function in 6 dogs under general anesthesia. METHODS: The dogs were anesthetized with halothane 1.0-1.5 volume %, nitrous oxide 2L/min and oxygen 2L/min. Epidural catheter was inserted via 17 gauge Tuohy needle through L2-L3 intervertebral space. The abdominal wall was opened and the left renal artery was dissected to measure the blood flow with the electromagnetic flowmeter. We measured mean arterial pressure, cardiac output, central venous pressure, pulmonary capillary wedge pressure and renal blood flow at the interval of 20 minutes for 2 hours during general anesthesia (control period). Urine had been collected for the control period, and then blood was sampled for the measurement of serum creatinine concentration from the femoral artery. Under the general anesthesia, epidural anesthesia was established using 10ml of 0.5% bupivacaine, and we measured same parameters for the same time sequence as in the control period (experimental period). RESULTS: Mean arterial pressure and cardiac output decreased significantly after epidural anesthesia (p<0.05). Central venous pressure and pulmonary capillary wedge pressure were not changed comparing to those in the control period. Renal blood flow decreased significantly after epidural anesthesia (p<0.05) but creatinine clearance and urine output were maintained. CONCLUSION: renal blood flow was decreased but renal function was maintained when epidural anesthesia reduced mean arterial pressure and cardiac output.