Approximately 30% of patients with chronic HCV infection show persistently normal alaninaminotransferase (ALT) levels. The majority of HCV carriers are females, and up to 40-50% of carriers harbor non-1 genotype, at least in western Europe. No association has been found between HCV type/viral load and the severity of liver damage. The prevalence of HCV carriers with normal liver seems to be very low (less than 20%). Liver disease is usually minimal/mild and fibrosis is generally absent or minimal, although the association of normal ALT with cirrhosis or with hepatocellular carcinoma has been reported. In all studies, liver histology was, on average, significantly less severe in subjects with persistently normal ALT than with abnormal ALT. Although the majority of data seem to show that HCV carriers with normal ALT have mild and stable disease, with a favourable prognosis, several studies reported a significant progression of fibrosis in approximately 20-30% of the patients with ALT normality, and the development of hepatocellular carcinoma in some cases has been described, despite persistent ALT normality. Sudden worsening of disease with ALT increase and histological deterioration has been described after up to 15 years of follow-up.