To investigate the prevalence and incidence of cholecystolithiasis in hepatitis B surface antigen-positive chronic liver diseases, a prospective study using hepatobiliary ultrasonography was conducted in 933 "healthy" persons and four groups of HBsAg-positive patients: 226 asymptomatic carriers, 73 patients with chronic active hepatitis, 77 patients with early liver cirrhosis and 124 patients with advanced liver cirrhosis. Patients with hepatocellular carcinoma or alcoholism were excluded. The prevalences of cholecystolithiasis increased along with the increasing duration and severity of chronic liver diseases, with a significant linear trend (p less than 0.001). The prevalences of cholecystolithiasis in patients with liver cirrhosis (18.5% in males, 31.2% in females) were 4 to 5.5 times higher than that of the healthy population (p less than 0.005). In addition, the linear trend of increasing prevalence with increasing age in the healthy population was not observed in patients with chronic liver diseases. On the other hand, five of the 69 patients with early liver cirrhosis were found to develop cholecystolithiasis during a mean follow-up period of 32 months. The calculated annual incidence of cholecystolithiasis was 2.6%. The results suggest that chronic liver disease, particularly liver cirrhosis, is a risk factor for cholecystolithiasis.