The effect of acute renal denervation on renal blood flow (RBF) and intrarenal distribution of blood flow (microsphere method) was studied in dogs using three standard denervation models. Surgical denervation, by stripping renal vascular nerves and autoperfusing the kidney through a large bore plastic catheter, caused RBF and glomerular filtration rate to decrease. Also, intrarenal distribution of blood flow became asymmetric, that is, perfusion changes in the two halves of the kidney were not similar. Denervation by stripping away the neural tissue and infiltrating the hilum with 0.5% procaine and 50% ethanol produced no adverse effects on RBF, but distributional changes were asymmetric. Denervation by this method was probably incomplete as evidenced by decreased RBF following bilateral carotid occlusion. Intrarenal arterial infusion of 10 µg/kg/min phenoxybenzamine caused renal perfusion to change asymmetrically and did not abolish the decrease in RBF normally seen following nerve stimulation. Present results demonstrate denervation studies must be interpreted cautiously; because the denervation model may cause renal damage and asymmetric perfusion, and denervation may not be complete