Recent studies have shown that atrial natriuretic peptide, which is a thrird factor that is important in electrolytes and volume homeostasis, is increased or decreased in patients with liver cirrhosis that complicate ascites or not. For further evaluation about levels and effects of circulating ANP in liver cirrhosis author measured simultaneously the plasma concentracion of α-hANP, renin activity, aldosterene by radioimmunoassay and 24-hour urine sodium levels in series of 22 patients with liver cirrhosis, and compared these values with those obtained in 18 normal controls. The results were as follows: 1) The plasma levels of α-hANP (pg/ml) in normal controls (18 cases), cirrhotics without ascites (10 cases), and cirrhotics with ascites (12 cases) were 71.56+-9.35, 73.62+-8.72, and 60.88+-8.60 respectively: and those of cirrhotics with ascites were significantly decreased(p<0.01). 2) In cirrhotics with ascites, plasma renin activity (ng/ml/hr) and plasma aldosterone levels (pg/ml) were 8.52+-2.70 and 303.50+-48.52 respectively and were significantly increased, as compared to those in the normal controls and cirrhotics without ascites(p<0.001). 3) There was no significant correltation between plasma α-hANP levels and renin activity in normal controls and cirrhotic patients (r= 0.45). 4) There was no significant correlation between plasma α-hANP levels and 24h excretion of sodium in normal controls and cirrhotic patients (r=0.225).