The combination of a beta blocker and a vasodilator is logical in the treatment of high blood pressure. Systemic arteriolar dilatation is beneficial to reduce the elevated peripheral resistance and hence to decrease cardiac afterload. beta-Adrenoceptor blockade exerts its own antihypertensive activity and also suppresses the reflex tachycardia induced by vasodilation. The combined beta- and alpha-adrenoceptor blockade exerted by carvedilol imposes these beneficial hemodynamic effects. Carvedilol is a nonselective beta-adrenoceptor antagonist, devoid of intrinsic sympathomimetic activity and possessing selective alpha 1-adrenoceptor-blocking activity, although this is considerably weaker than its beta-adrenoceptor antagonistic activity. One isomer [S(-)-carvedilol] contains both the beta- and alpha-adrenoceptor activity, whereas R(+)-carvedilol is only a weak alpha blocker. Carvedilol is produced as the racemate. The hemodynamic profile is in accordance with that to be expected from the combination of beta and alpha blockade.