The incidence of opportunistic infectious diseases and the mortality rate associated to the HIV infection have greatly decreased with the wide use of the Highly Active Antiretroviral Therapy (HAART). However, the "Mortalité 2000" study conducted in France on the causes of deaths in the HIV infected population has revealed that 47 % of deaths were still due to an opportunistic infection, whereas 50 % of them are not associated with the HIV infection (the four main causes being cancer, chronic hepatitis C, cardiovascular diseases and suicide). The longer life expectancy of patients treated with HAART has lead to an increased frequency of complications due to chronic viral B and C hepatitis. The higher prevalence of hepatitis viral infections in the HIV-infected patients implies to methodically screen this population for HCV and HBV markers, and consequently modify the clinical and therapeutic management of co-infected patients.