We investigated the seroprevalence of HCV in stable sexual partners and offspring of chronic hepatitis C patients, and aimed to determine the risk factors involved. 191 anti-HCV and HCV RNA positive subjects who coinhabited with their spouse and/or offspring were included. Risk factors of index cases for disease transmission, liver biopsy results, anti-HCV and HCV-RNA in spouses and/or offspring were evaluated. Together with index cases, a total of 404 family members including 174 stable sexual partners and 230 offspring were included. The most common risk factors among index cases were dental procedures (73.8%), history of surgery (64.9%), and blood transfusions (24.1%). Anti-HCV positivity was established in 11 (2.7%) of the total 404 family contacts--6 sexual partners and 5 offspring. HCV seropositivity was significantly higher in the spouses of index cases with severe hepatitis C compared to those with mild to moderate hepatitis C (p=0.008), but there was no statistically significant correlation between the severity of liver disease in index cases and anti-HCV positivity in their offspring. In conclusion, anti-HCV seropositivity in the spouses and children of patients who are HCV-RNA positive HCV carriers does not appear to be higher than the HCV seroprevalence in our country.