Non-organ-specific autoantibodies (NOSAs) are frequently found in patients with hepatitis C virus (HCV) chronic infection. Genetics is likely involved in the development of autoimmune reactivities, and differences in the prevalence of HCV-related autoantibodies among populations of various geographic areas should be expected. We evaluated the prevalence and the clinical impact of NOSAs in a series of HCV-infected patients from southern Italy. We studied 283 consecutive anti-HCV positive patients (162 men, 121 women, mean age 54.5 +/- 13.5 years), 94 of whom were cirrhotics and 189 noncirrhotics. Serum from each patient and from 41 hepatitis B surface antigen (HBsAg)-positive/anti-HCV negative control subjects were tested (dilution 1:40) for autoantibodies by indirect immunofluorescence. Qualitative/quantitative HCV-RNA determinations were also performed. The prevalence of NOSAs was significantly higher in anti-HCV-positive subjects than in HBsAg-positive patients (P < 0.006). Autoantibodies were significantly associated with both cirrhosis (P < 0.0001) and older age (P < 0.05). No significant association between NOSAs and either female gender or virological parameters (HCV-RNA positivity, viral load, and genotype) was found. In conclusion, the autoantibody positivity in HCV-infected patients from southern Italy is significantly related to cirrhosis and older age, although its general prevalence is similar to that reported in populations from the north of the country.