 Approximately 20-25 of the total number of HIV-infected patients is co-infected with HCV which translates to 6-8 million persons worldwide. Combined treatment of HIV and HCV is complicated by the risk of drug-drug interactions as both the direct acting antiviral agents DAAs for HCV as the antiretroviral agents for HIV are substrates of cytochrome P450 CYP450 or various membrane transporters, and also have the capacity to influence these systems. A careful selection of the appropriate regimens and if needed adjusted doses is key for optimal treatment of both viral infections. 