The rate of intrafamilial transmission of the hepatitis C virus (HCV) was investigated in 90 family members of 41 index patients with type C chronic liver disease. Antibody to HCV (anti-HCV) was detected by the EIA method (Abbott-Axsym Sys) and Hepatitis C virus RNA, by the polymerase chain reaction (Nested PCR). We also investigated the presence of anti-HCV in 350 healthy persons (control group). The subjects in the study included 38 spouses, 45 children and others (1 relative and 6 parents). Four family members including 3/38 (7.8%) spouses and 1 sister were found to be positive for anti HCV antibodies but none had HCV RNA. Anti-HCV was not detected in the children of index patients. The prevalence of anti-HCV in the families of index patients was significantly higher than in the controls (4.3% versus 0.85%) (p = 0.0355). We concluded that the intrafamilial transmission of HCV is possible but occurs at a low rate.