This study evaluates systemic and splanchnic haemodynamics and the effect of propranolol in 15 patients with presinusoidal portal hypertension (portal vein obstruction, n = 11; schistosomiasis, n = 4). These patients exhibited a hyperkinetic circulatory syndrome characterized by high cardiac index (4.4 +/- 1.61.min-1.m-2, mean +/- S.D.) and by low systemic vascular resistance despite normal liver function and sinusoidal pressure. Hepatic blood flow was decreased in half of the patients with portal vein obstruction. Azygos blood flow, an estimate of superior portal-systemic collateral circulation, was markedly increased in all patients (0.46 +/- 0.19 l/min, upper limit of normal: 0.19 l/min). Therefore, in these patients with normal hepatic venous pressure gradient, azygos blood flow measurement provides an index of splanchnic haemodynamic changes. Propranolol administration (15 mg, i.v.) reduced the hyperkinetic circulatory syndrome, with a significant decrease in heart rate (-17 +/- 6%), cardiac index (-25 +/- 12%) and azygos blood flow (-40 +/- 26%) and a significant increase in systemic vascular resistance (+40 +/- 40%). These results suggest that the hyperkinetic circulatory syndrome observed in these patients, could be related to an increase in beta-adrenergic activity. The decrease in azygos blood flow, after propranolol administration, was significantly correlated (r = 0.94) with the increase in right atrial pressure. This finding suggests that propranolol may act through an increase in portal-systemic collateral venous tone. These haemodynamic results justify, in patients with presinusoidal portal hypertension, clinical trials investigating the beneficial effect of beta-blockers on gastrointestinal bleeding caused by portal hypertension.