Increased concentrations of serum hyaluronan, a polysaccharide widely distributed in the extracellular space, have been demonstrated in liver disease of various aetiologies and proposed as a useful marker of liver fibrosis. The aim of the present study was to evaluate the association of serum hyaluronan with the extent of hepatic fibrosis in asymptomatic cases of chronic hepatitis B viral infection. The study was conducted in a consecutive sample of 111 asymptomatic chronic carriers of hepatitis B surface antigen. Liver function tests, alcohol consumption and cigarette smoking were determined and, for 84 subjects, liver biopsy was performed and degrees of inflammation and fibrosis were scored. Hyaluronan was measured using a radiometric assay. Mean serum hyaluronan increased with increasing fibrosis score (from 22.2 +/- 4.8 to 50.6 +/- 12.7 microg/l, p = 0.058) or pathological severity (from 18.8 +/- 5.9 to 50.6 +/- 12.5 microg/l, p = 0.048), even after adjusting for the effect of age. No such correlation was found with portal inflammation. The study showed that, in asymptomatic chronic carriers of hepatitis B, serum hyaluronan concentration correlates with hepatic fibrosis, a known marker of disease prognosis. This finding supports the hypothesis that hyaluronan might be of use in assessing and monitoring time trends in liver disease, substituting for repeated biopsies.