Both hepatitis B virus (HBV) and hepatitis C virus (HCV) are more common in HIV-infected individuals than in the general population as a result of shared risk factors for viral acquisition. Populations of injecting drug users are at particularly high risk for HIV/HCV co-infection. Co-infection with HIV results in greater likelihood of chronicity and enhanced viral replication in the setting of both HBV and HCV infections. Current evidence suggests that HIV infection may have a negative impact on HBV-related liver disease progression, although the mechanisms for this are unclear. HBV seems to have little impact on the progression of HIV disease. HIV co-infection hastens HCV-related liver disease with faster progression to cirrhosis, end-stage liver disease and occurrence of hepatocellular carcinoma. There is still conflicting evidence on the impact of HCV on HIV progression with inconsistent results from cohort studies. Long-term follow-up of highly active antiretroviral therapy (HAART)-treated patients will help elucidate this further. Antiretroviral agents have little long-term impact on HCV viraemia, although some have significant anti-HBV activity. Morbidity and mortality from end-stage liver disease in HIV-infected individuals is increasing and every effort should be made to identify, educate and treat as appropriate those with HBV or HCV co-infection.