In nine patients with decompensated alcoholic cirrhosis of the liver and impaired renal function the effect of 8‐ornithin vasopressin (ornipressin) on renal function and haemodynamic parameters was studied. Ornipressin was infused at a dose of 6 IU/h over a period of four hours. During ornipressin infusion an improvement of renal function was achieved as indicated by an increase of creatinine clearance (76 (15)%; p < 0.01), urine volume (108 (29)%; p < 0.05) and sodium excretion (168 (30)% p < 0.05). The hyperdynamic circulation of hepatic failure, as characterised by in creased systemic vascular resistance was reversed to a nearly normal circulatory state during ornipressin infusion. The raised noradrenaline plasma concentration (1.74 (0.31) ng/ml) and plasma renin activity (13.5 (3.9) ng/ml/h) were lowered during ornipressin infusion to 0.87 (0.21) ng/ml and 5.9 (2.1) ng/ml/h, respectively (p < 0.01). The efficacy of a vasoconstrictor agent in reverting a hyperdynamic state and improving renal function provides evidence for the substantial role of accumulation of vasodilator substances and subsequent activation of sympathetic nervous system and reninangiotensin‐axis in the pathogenesis of renal dysfunction in hepatic failure. Values are expressed as mean (SE).