We tested 50 heterosexual partners of hepatitis C viraemic (HCV) individuals, using second generation HCV antibody assays and a validated polymerase chain reaction assay. In none of them were HCV antibodies or HCV-RNA detected. The median duration of the sexual relationship was 13 years. This study, with the most sensitive techniques for detection of HCV, indicates that the risk of sexual transmission of HCV is absent or very low.