The significance of changes in plasma somatostatin level at patients with vascularly decompensated liver cirrhosis was investigated. The plasma level of somatostatin, glucagon, gastrin and blood glucose concentration were determined under basal condition and after testmeal in patients with vasculary decompensated cirrhosis, in cirrhotic-patients without ascites formation and in control subjects. The basaline levels and the postprandial increases of plasma somatostatin concentrations were significantly lower in cirrhotic patients with ascites, compared to the other two groups. The glucagon concentrations--both the basaline and the postprandial--were significantly higher in the cirrhotic patients-groups, compared to the controls. The gastrin and blood glucose levels were not different in the three groups. The decrease in plasma somatostatin concentration present in cirrhosis associated with ascites represents a secondary phenomena, and suggest that endogen somatostatin plays a role in maintaining body fluid homeostasis.