Little is known about the effect of posture on the circulatory abnormalities of advanced cirrhosis. We evaluated the systemic hemodynamics, measured by Doppler-echocardiography, atrial natriuretic factor, plasma renin activity and plasma norepinephrine, in 10 patients with cirrhosis and ascites and 10 healthy controls, after 2 h of standing and during lying down for a further 2 h. Standing hemodynamic patterns of controls and patients with cirrhosis did not differ significantly. The latter, however, showed higher plasma renin activity, norepinephrine and atrial natriuretic factor. The assumption of the supine position led to greater increases in cardiac index and atrial natriuretic factor, and reduction in systemic vascular resistance in patients with cirrhosis. Norepinephrine and plasma renin activity declined in both groups to a similar extent, while heart rate only slowed in controls. Thus, after 2 h in the supine position, patients with cirrhosis showed hyperdynamic circulation with increased cardiac index and heart rate and reduced systemic vascular resistance. Norepinephrine, plasma renin activity and atrial natriuretic factor were also elevated. The hyperdynamic circulation in advanced cirrhosis appears during or is enhanced by lying down. This finding suggests that this syndrome is, at least in part, attributable to excessive blood volume translocation towards the central area. However, the persistent activation of renin-angiotensin and sympathoadrenergic systems suggests that a concomitant reduced vascular sensitivity to vasoconstrictors concurs in its development.