Summary. To report the prevalence and the risk factors for hepatitis C virus (HCV) infection in a hospital cohort of 2691 sexually human immunodeficiency virus (HIV)-infected patients. The patients were enrolled in the Lyon section of the French Hospital Database on HIV between 1992 and 2002. Baseline characteristics were analysed. The detection of HCV-antibodies (Ab) was used for diagnosis. The HCV-Ab prevalence rate was 5.7 and 12.89% for individuals infected by HIV after homosexual intercourse or heterosexual intercourse, respectively. HCV-Ab was three times more frequently found among patients infected with HIV after heterosexual intercourse compared with patients infected with HIV after homosexual intercourse (adjusted OR: 3.2, 95% CI: 2.28–4.62, multiple logistic regression). The risk of HCV infection among HIV-infected individuals differed according to sexual behaviour. The determinants associated with HCV transmission through the sexual route needs to be explored further.