Abstract OBJECTIVE: To study the specific impact of treatments for chronic hepatitis C virus (HCV) infection on anger expression and control in adult patients coinfected with HIV and HCV receiving antiretroviral therapy. DESIGN: In 2005, a cross-sectional survey, collecting both clinical and sociobehavioral data, was conducted in two French clinical centers among adult patients coinfected with HIV and HCV. METHODS: Participants were asked to answer anonymously a self-administered questionnaire aimed at obtaining sociodemographic, clinical and behavioral characteristics including self-reported treatments’ side effects, quality of life (WHOQOL-HIV BREF), and irritability and anger (STAXI-2). Clinical characteristics were obtained from medical records. RESULTS: Among the 139 patients who were receiving antiretroviral therapy at the time of survey and who had complete self-reported data, 24 were being treated for their HCV infection, using either pegylated interferon (pegIFN) and ribavirin (RBV) or pegIFN alone. Control of anger was significantly lower among treated patients than among untreated ones (STAXI-2 anger control-out dimension median scores of 18.5 versus 23 respectively, P = 0.02). Sociodemographic and clinical characteristics did not differ significantly between these 2 groups. Control of angry feelings was significantly correlated with psychological and social relationship dimensions of quality of life. CONCLUSION: Treatment of HCV-HIV co-infected patients may require closer monitoring for anger control issues and adjustment of treatment as appropriate.