We aimed to determine serum soluble Fas antigen (sFas) levels at various stages of hepatitis C virus (HCV)-induced liver disease, and investigate correlations between serum sFas levels and clinical, biochemical and pathologic features. Sixty-five patients were categorized into five groups: 1, chronic active hepatitis C, elevated alanine aminotransferase (ALT), HCV-polymerase chain reaction (PCR) positive; 2, responders to interferon + ribavirin therapy; 3, cirrhosis; 4, chronic hepatitis C, normal ALT, HVC-PCR positive; and 5, sustained responders. Group 6 comprised 15 control individuals. Serum sFas levels were measured by enzyme-linked immunosorbent assay. Significant differences in serum sFas levels were found between the following groups: 1 and 2; 1 and 3; 1 and 4; 1 and 6; and 3 and 6. Serum sFas levels did not correlate with ALT, histological activity or HCV-PCR positivity within group 1. Serum sFas levels appear to increase in advanced stages of HCV-induced liver disease, as a result of host-related immunological factors.