Circulating immune complexes (CIC) were investigated by the fluid-phase C1q-binding test in serum samples from 131 subjects with various clinical types of HBsAg-positive and HBsAg-negative chronic hepatitis diagnosed on both clinical and laboratory criteria, including liver biopsy; serum samples from 28 asymptomatic HBsAg carriers and 75 healthy controls were also examined. The results of these findings were correlated with the liver damage and the clinical course of the disease. CIC were detected in all categories of chronic hepatitis with a significant prevalence only in patients with liver cirrhosis. No correlation was found between the levels of CIC, the presence of circulating HBsAg, and active inflammation or necrosis in any of the different types of chronic hepatitis. In contrast, a highly significant correlation was found between the prevalence of CIC and a more severe prognosis in patients with CAH and liver cirrhosis. The findings suggest that the presence of CIC is not specific for a given type of chronic liver disease and that they do not play any role in the pathogenesis of liver damage. The correlation observed between the presence of CIC and an unfavourable course of chronic liver disease suggests that CIC may modify the host's immune defence mechanisms.