The effect of a standardized test meal on portal haemodynamics was measured by duplex ultrasonography in healthy subjects (12 men and 13 women; mean age 43 +/- 9 years) and patients with liver cirrhosis (14 men and 11 women; mean age 55 +/- 10 years). Maximal flow velocity, vessel diameter and flow volume were measured in the portal vein and superior mesenteric artery before the test meal and 15, 30 and 45 min thereafter. After a 12-hour fasting period maximal flow velocity in the portal vein was significantly lower in the cirrhosis patients than the normal subjects (P less than 0.05), but the individual values clearly overlapped. 30 min after the test meal flow velocity in the portal vein rose by 22%, flow volume by 29% in the cirrhosis patients, but by 76% and 131%, respectively, in the normal controls (P less than 0.01). Vessel diameter remained constant in the patients, but increased significantly in the controls (P less than 0.05). There was no overlapping of values between the two groups. The increase in flow velocity in the superior mesenteric artery was nearly the same in both groups. It is concluded that, after a test meal the haemodynamic differences between normal subjects and cirrhosis patients becomes quite marked and thus can provide a more exact diagnosis of portal hypertension by duplex ultrasonography.