Co-infection of HIV and hepatitis viruses is frequent due to common transmission routes. This sharing goes far beyond epidemics and may have important clinical implications. The course of chronic viral hepatitis B and/or C is accelerated in immune deficient patients, with faster progression to end-stage liver disease. On the other hand, response to antivirals against hepatitis is poorer in the HIV setting. Finally, the toxicity of antiretroviral drugs is increased in patients with underlying chronic viral hepatitis. The good news is that many of the most recent antiretroviral agents have a good hepatic safety profile, and immune restoration using potent antiretroviral therapy may revert, to some extent, the deleterious consequences of co-existing viral infections.