1 Intravenous loading with 500 ml of 2.7% saline increased the clearance of PAH and inulin and urine sodium excretion in 14 healthy subjects. 2 Intravenous propranolol (0.075 and 0.15 mg/kg) did not alter PAH or inulin clearance at rest but abolished the increase expected during saline infusion. There was no consistent effect on urinary sodium excretion. 3 Intravenous nadolol (0.05 and 0.75 mg/kg) reduced resting PAH and inulin clearances by up to 25%. Both clearances fell significantly during saline infusion but natriuresis was not significantly reduced in spite of the changes in renal function. 4 There was no evidence from these studies in normal volunteers that nadolol confers any advantages over propranolol in its effects on renal function.