In 255 patients with acute viral hepatitis and in 50 healthy controls, wall thickness, volume, and percentage of maximal contraction of the gallbladder were prospectively evaluated using real-time ultrasonography. A hypotonic, hypokinetic gallbladder was shown in 58.4% of the cases, expressed by normal parietal thickness, larger volume, and lower response to fat stimulation than the controls. In the remaining patients, wall thickening, decreased volume, and reduced contraction were compatible with a hypertonic gallbladder. Because the latter pattern was never observed in patients with disease onset dating back more than 9 days, it is conceivable that gallbladder hypertonicity in the early phase of the illness is followed by depression of tone and motor activity. However, such sonographic features turned out to be short-lived and reversible as they disappeared in all patients within 3 weeks of the first ultrasound examination. Moreover, none of the sonographic abnormalities correlated with either biochemical indices of acute disease or the patients' long-term outcomes.