HCV infection among heterosexuals with multiple partners and family members of patients with hepatitis C, and HCV RNA in the body fluid of these patients were investigated. The results showed that the HCV infection in heterosexuals with multiple partners, which was related to sexual activity, was much higher than that of healthy pregnant women. The HCV RNA in the saliva, semen or vaginal discharge of patients with hepatitis C was at detectable level. Among the patient's relatives, none of the children but 2 spouses were found to be infected with HCV. We concluded that sexual contact might play some role in HCV transmission.