Five patients with newly diagnosed hypertension treated with Labetalol in various dosage were assessed at fortnightly intervals after starting therapy to determine if any alteration in renal function had occurred. Before therapy, 2 patients had a normal glomerular filtration rate, one had a glomerular filtration rate of 71 mls/min and 2 had severe impairment of renal function with glomerular filtration rates of less than 20 mls/min. A significant increase in glomerular filtration rate was observed within 2 weeks of starting Labetalol which persisted with continuing therapy. Effective renal plasma flow increased significantly only at the fourth week stage. No significant alteration of serum urea or creatinine was observed. Blood pressure was well controlled in each case and side effects were minimal. It is suggested that Labetalol does not impair renal function in hypertensive patients and may actually improve the glomerular filtration rate.