Aim of the study was to identify the different hepatitis C virus (HCV) genotypes in chronic hepatitis patients living in the districts of Messina and Catania (Sicily, Italy), for epidemiological reasons but also to determine the effect of interferon therapy on therapeutic response of different viral genotypes. Genotyping was carried out by reverse-hybridization after amplification by polymerase chain reaction. The study was conducted on 271 patients with HCV-RNA positive chronic liver disease belonging to categories at risk or not for infection. HCV genotype sub-type 1b was the most common viral genotype identified.