We assessed the effects on renal haemodynamics in 18 black patients with essential hypertension of acute and chronic β-adrenergic blockade with three agents having different properties: atenolol, nadolol or propranolol. Six patients received each drug. In our patients the antihypertensive response to β-blockers was minimal or nonexistent. This permitted us to analyse the effects on renal haemodynamics of 'pure' β-blockade, as opposed to the combined effects of β-blockade and decreased systemic perfusion pressure. In this setting, neither acute nor chronic administration (two months) of each of these agents decreased renal perfusion. We conclude, therefore, that β-blockade per se has no deleterious effect on renal function and previous observations are most probably accounted for by the blood pressure lowering effect of these drugs, either alone or coupled with β-blockade of the renal vasculature allowing unopposed α-sympathetically mediated vasoconstriction.