Prospective study of gallbladder wall thickness by ultrasonography was performed in 38 patients of acute viral hepatitis and 50 normal sugjects as a control group from June 1983 to April 1984. The results were as follows; 1. In normal population, the range of gallbladder wall thickness is from 1 mm to 3mm with peak incidence in 2mm (66%, 33 case) Mean thickness of gallbladder wall is about 1.9$pm$ 0.6mm 2. In acute viral hepatitis, the range of gallbladder wall thickness in from 2mm to 8mm with peak incidence in 3mm (34%, 13 case), second peak in 4mm (29%, 11case) Mean thickness of gallbladder wall is about 3.6$pm$1.6mm, which is thicker than normal with statistical significance. (p<0.005) 3. In acute viral hepatitis, the mean thicknes 낼 glabladder wall is about 4.4$pm$1.8mm in the group of SGOT/SGPT level above 400 IU, and 2.8$pm$0.8mm in the group of SGOT/SGPT level below 400 IU. this difference is significant statistically (p<0.05)