Intrafamilial transmission of hepatitis C virus (HCV) was studied in family members of 44 children with chronic hepatitis C infection (index cases). There were 22 males and the mean age of all patients was 9.5 years (range, 1.5 to 16 years). Eleven index patients were multitransfused because of thalassemia major. Aminotransferase serum concentrations and anti-HCV antibodies were evaluated in 77 parents (38 fathers) and 56 siblings (28 males; mean age, 11.2 years; range, 2.5 to 18 years). No sibling showed evidence of liver disease or HCV infection. Eight parents (14%) were found to be anti-HCV positive, but only one of them acquired HCV infection from an index case through an accidental needle stick injury. A nonsexual person-to-person tran...