To determine the importance of hepatitis C virus (HCV) infection in the aetiology of chronic liver disease in southern India, the prevalence of HCV antibodies and HBV markers was estimated in 100 patients with chronic liver disease and in 56 patients with a variety of other gastrointestinal and liver diseases who served as controls. HCV antibody was measured by a second-generation ELISA. HBsAg, anti-HBc, anti-HBs and anti-D were also estimated. HCV antibodies were detected in 26/100 patients with chronic liver disease compared to 0/56 controls. HBV markers were present in 72 of 100 patients with chronic liver disease compared to 21/56 (37.5%) controls. Anti-D was noted in 4/100 patients with chronic liver disease and in none of the controls. Many patients had serological evidence of both B and C infection; 73% of those with anti-HCV also tested positive for HBV markers. HCV related disease presented at a median age of 60 years compared to HBV related disease which presented at a median age of 40. There was no significant difference between HCV and HBV positive patients in symptomatology, but encephalopathy was uncommon and cirrhosis the usual finding at histology in HCV positive individuals, while chronic active hepatitis was found in 30% of biopsied HBV related disease. HCV is a significant cause of chronic liver disease in this geographic region, although HBV infection continues to account for the largest proportion of cases.