In the initial phase of heart failure, cardiac output and pressure are maintained by increasing sympathetic drive and by cell hypertrophy. Elevated end-diastolic volume, a reduced ejection fraction and a higher filling pressure also occur. Only in more severe heart failure when cardiac output cannot be maintained do symptoms appear which may vary between congestion, exercise intolerance, left ventricular dysfunction, arrhythmias or a combination of each. Drug treatment has principally two aims: first, to improve symptoms, second to influence prognosis, which is very poor in advanced heart failure. Symptom improvement will also depend on whether the condition is acute, subacute or chronic heart failure. In the acute situation diuretics are normally the first choice of treatment, whereas in chronic heart failure the ACE inhibitors have proved themselves to be the drugs which most improve prognosis. The role of digitalis, still frequently used, remains unclear, and its importance will be revealed when the results of ongoing studies are announced.