Enalapril provides significant haemodynamic, symptomatic and clinical improvement when added to maintenance therapy with digitalis and diuretics in patients with congestive heart failure [NYHA (New York Heart Association) classes II to IV]. These effects are not attenuated during long term therapy. More significantly, a clinical study demonstrated that enalapril reduces mortality when added to established therapy in patients with severe congestive heart failure (NYHA class IV) refractory to digitalis, diuretics and other vasodilators. Thus, ACE inhibitors such as enalapril offer a significant advance in the treatment of congestive heart failure. Because these drugs improve symptoms in patients with classes II to IV failure, and reduce mortality in patients with severe heart failure, they should be considered as first choice adjuvant therapy when a vasodilator is needed in addition to conventional treatment with digitalis and diuretics.