In the past several years great progress has been made in the understanding of the (patho) physiology of ANP. Because an inhibitor of ANP is not available for human use, there is still discussion about the physiological role of ANP. Nevertheless, from the studies described above the evidence is accumulating that ANP has a role in protecting against fluid overload and hypertension by means of inducing natriuresis, inhibition of the renin-angiotensin-aldosterone system and vasopressin and by vasodilation. The therapeutic potential of modulation of the ANP system seems promising, but must await further research.