In cardiac failure unresponsive to digoxin and diuretics, afterload reduction brings about a dramatic increase in cardiac output, renal perfusion and responsiveness to diuretics; furthermore, the decrease in venous pressure relieves the dyspnoea. Intravenous vasodilators should only be used when sophisticated haemodynamic monitoring equipment and experienced physicians are at hand. Indications for the use of these agents are severe cardiac failure, acute myocardial infarction complicated by left ventricular failure, persistent ischaemic pain and limitation of infarct size. A wide variety of oral vasodilator agents is available, all having different sites of action; the choice of vasodilator agents should be tailored to the needs of the patient. Treatment with these agents is indicated in patients in whom cardiac failure becomes refractory to conventional therapy with digoxin and diuretics. The utmost care must be taken to avoid further impairment of cardiac output by excessive reduction of the left ventricular end-diastolic pressure (LVEDP) and hypotension, which will jeopardize myocardial, renal and cerebral perfusion.