Unlike many vitamins derived predominantly from food sources, vitamin D is produced endogenously in the skin upon exposure to sunlight. Ethnicity, skin pigmentation, socioeconomic status, geographic location, climate and sunscreen; all of these factors contribute to the amount of insolation for any given individual. Insufficient insolation creates the prerequisites for vitamin D deficiency. This is particularly true in HIV-infected individuals, who are highly vulnerable to vitamin D insufficiency/deficiency, as it plays a huge role in the musculoskeletal and cardiovascular systems. Antiretroviral therapy may also be a factor in vitamin D deficiency. Today, as the issues of preventing common skeletal and non-skeletal diseases with HIV-infected people are becoming highly relevant, the maintenance of vitamin D levels through exposure to sunlight or supplementation appears to be an effective and safe solution. This review focuses on studies concerning the potential role of vitamin D supplementation through adequate sunlight exposure or dietary intake in HIV-infected people. The biology and epidemiology of HIV infection, as well as the issues related to vitamin D deficiency, its status on immune function, the effect of vitamin D against HIV disease progression and other health aspects of this vitamin, are briefly explained.