Hepatitis C virus infection in infancy largely depends on vertical transmission. The transfer of hepatitis C virus from mother to child is almost invariably restricted to children whose mother is viremic, and the rate of transmission seems to be influenced by maternal virus load, although, in the single patient, the levels of viremia cannot be used as predictors of pediatric infection. In fact, the flow-chart for screening children at risk for vertically transmitted hepatitis C virus infection takes into account maternal viremia. In children born to anti-hepatitis C virus antibody positive, hepatitis C virus-RNA negative mothers, alanine aminotransferase and anti-hepatitis C virus should be investigated at 18-24 months of life. If alanine aminotransferase values are normal and anti-hepatitis C virus is undetectable, follow-up should be interrupted. In children born to hepatitis C virus-RNA positive mothers, alanine aminotransferase and hepatitis C virus RNA should be investigated at 3 months of age: (1) hepatitis C virus-RNA positive children should be considered infected if viremia is confirmed by a second assay performed within the 12th month; (2) hepatitis C virus-RNA negative children with abnormal alanine aminotransferase should be tested again for viremia at 6-12 months, and for anti-hepatitis C virus at 18 months; (3) hepatitis C virus-RNA negative children with normal alanine aminotransferase should be tested for anti-hepatitis C virus and alanine aminotransferase at 18-24 months, and should be considered non-infected if alanine aminotransferase is normal and anti-hepatitis C virus undetectable; (4) anti-hepatitis C virus seropositivity beyond the 18th month in a never-viremic child with normal alanine aminotransferase is likely consistent with past hepatitis C virus infection.