The atrial natriuretic factor (ANF) is a vasodilating and natriuretic peptide. In experimental and human cardiac failure, plasma ANF concentrations are increased. The ANF is a good marker of functional and haemodynamic severity and of the prognosis of cardiac failure. In this syndrome, messenger RNA of ANF is expressed not only in the atria but also in the ventricles which also secrete the peptide. Attenuation of the natriuretic response is observed in cardiac failure. It may be related to an abnormality situated after the receptor and second messenger, cyclic GMP and/or the reduction of renal perfusion pressure which occurs in cardiac failure. The therapeutic perspectives of ANF in cardiac failure are limited by the necessity of continuous intravenous or parenteral administration. Inhibitors of the enzyme degrading the peptide, neutral endopeptidase, are under evaluation in clinical trials which are at a preliminary stage for the moment.