Osteopenia, osteoporosis, and osteonecrosis are the most significant bone disorders affecting patients with human immunodeficiency virus (HIV) infection. HIV-infected patients receiving potent antiretroviral therapy have a high prevalence of reduced bone mineral density (BMD). However, patients not receiving antiretrovirals also have a higher than expected prevalence of reduced BMD, which suggests that HIV itself may be a contributing factor, mediated by immune activation and cytokines. The risk of fractures remains undefined in this population, and no data exist on interventions to increase BMD and prevent fractures. Osteonecrosis has been reported in HIV-infected patients since 1990, and its incidence appears to be increasing. Available data suggest that corticosteroid use and other risk factors contribute significantly to its pathogenesis. Controlled studies have not supported the contention that protease inhibitors increase the risk of osteonecrosis. An improved understanding of the pathogenesis of these bone disorders should result in better preventative and therapeutic measures.