Osteopenia and osteoporosis are the most important bone disorders affecting patients with HIV infection. The available data indicate that HIV-infected patients have a high prevalence of low bone mineral density. Reduced bone mass and alterations of bone metabolism have been found in HIV-infected children, adolescents and adults. The variety and complexity of changes in bone metabolism in patients with HIV infection and the different possible mechanisms triggering bone mineral loss, as well as the different stages of disease and cumulative exposure to antiretroviral drugs at the time of clinical evaluation, may contribute to the wide range of mineral loss observed and to the uncertainty of the role of specific antiretroviral medications.