The effect of beta-blockade was studied in 3 different kinds of human hypertension: borderline, sustained and isolated systolic hypertension. Young patients with borderline hypertension had a similar decrease in cardiac output with both nonselective and selective beta-blockade. Only nonselective beta-blockade decreased brachial artery blood flow and increased forearm vascular resistance. In patients with sustained essential hypertension, chronic administration of 2 nonselective beta-blockers, propranolol and pindolol, caused a similar significant decrease in blood pressure with different effects on forearm circulation. Pindolol produced a significant vasodilation of both large and small arteries of the forearm while propranolol did not. In patients with isolated systolic hypertension, short-term beta-adrenergic blockade with propranolol had different effects according to age. In younger patients, propranolol significantly decreased systolic pressure with a concomitant increase in rapid ventricular ejection. In older patients, a lack of systolic pressure reduction was observed with an increase in total peripheral resistance and a decrease in systemic arterial compliance. The results suggested that beta-adrenergic blockade in hypertension may affect blood vessels with different effects, according to age, to the characteristics of hypertension and to the specific properties of the beta-blocking agent. The vascular effects involve not only resistive vessels but also large arteries.