As human immunodeficiency virus (HIV) and hepatitis B virus (HBV) are acquired through the same routes of contamination, the prevalence of HBV serological markers found in the HIV-infected population is approximately 7 %. Liver-related mortality and morbidity is higher in HIV/HBV co-infected patients than in HBV mono-infected patients. Both viruses must be considered before a treatment decision is made. According to the European consensus conference on the treatment of chronic hepatitis B and C in HIV co-infected patients, treatment is based on whether there is an existing indication of anti-HIV therapy or not. In patients with no indication of anti-HIV therapy, drugs with dual anti-viral activity (lamivudine, entecavir, tenofovir disoproxil fumarate) should not be used due to the risk of developing HIV-resistance. Interferon or adefovir in combination with telbivudine are recommended. In patients with an indication of anti-HIV therapy, a backbone of highly active anti-retroviral therapy should include tenofovir in combination with lamivudine or emtricitabine. The same regimen is recommended in patients who develop lamivudine resistance. (C) 2010 Elsevier Masson SAS. All rights reserved.