The acute effects of captopril in cirrhosis are well known but there are few descriptions of the pattern of response to chronic administration of captopril in this disease. Nine nonuraemic cirrhotic patients with ascites and portal hypertension were studied after 1 week on fixed sodium and water intake (balance diet) and following acute and chronic treatment with captopril (three doses of 25 mg every 30 min and 75 mg.day-1 for three weeks, respectively). Whilst on the balance diet, 7/9 patients were unable to excrete the amount of sodium ingested. After the acute administration of captopril, a significant reduction was seen in arterial blood pressure (86.9 vs 77 mm Hg), with no change in the intra-hepatic pressures (free suprahepatic pressure, FSHP: 15.0 vs 12.1 mm Hg and wedged suprahepatic pressure, WSHP: 22.9 vs 20.7 mm Hg). After chronic captopril treatment, a drop was observed in portal pressure (FSHP: 9.4 mm Hg and WSHP 18.8 mm Hg, NS) and the arterial pressure returned to its basal level. The plasma aldosterone concentration decreased, whilst noradrenaline and dopamine increased significantly, the latter more than the former, leading to a reduction in the noradrenaline/dopamine ratio (14.5 vs 5.0). Seven out of nine patients showed enhanced natriuresis and the remaining two, who previously had had a positive sodium balance failed to do so. These haemodynamic, hormonal and renal changes were interpreted as evidence of blockade of angiotensin II generation by captopril, and also as a homoeostatic response by the sympathetic nervous system.