Doppler sonography measurement of portal flow velocity (PFV) after glucagon injection was performed in 45 patients with chronic hepatitis C virus (HCV) infection. Patients were divided into three groups: group 1 = no or mild liver fibrosis; group 2 = moderate to severe liver fibrosis, and group 3 = liver cirrhosis. All patients were examined using a Doppler ultrasound (US) multipurpose equipment and a convex 3.5-MHz probe, 10 min before (baseline), as well as 5 and 10 min after, IV administration of 1 mg of glucagon chloride. No significant differences were found in mean baseline PFV among group 1 (19.4 +/- 2.4 cm/s), group 2 (20.1 +/- 3.6 cm/s) and group 3 (17.5 +/- 3.7 cm/s). Five minutes after glucagon injection, all three groups showed significantly increased values of mean PFV (25.6 +/- 4.8, 23.7 +/- 4.0 and 19.5 +/- 5.0 cm/s, respectively; p < 0.05 vs. baseline). The mean increase of PFV above baseline was significantly higher in group 1 (7.9 +/- 3.7 cm/s) than in group 2 (4.5 +/- 3.9 cm/s) (p < 0.05) or in group 3 (2.7 +/- 2.3 cm/s) (p < 0.05). A significant inverse correlation was found between individual values of fibrosis score and of individual increase of PFV. In patients with chronic HCV infection, Doppler sonography measurement of PFV after glucagon injection could be useful in assessing the severity of liver histological damage.