Among environmental factors related to pathogen infection, vitamin D is largely considered to be protective and promoter of good health. For these reasons, a general concern exists about vitamin D insufficiency that has been found around world reaching epidemic dimensions. In the last few years, interest about the role of vitamin D on immune response has been increased after encouraging data illustrated the well-known contribution of the binomial sunlight exposure/vitamin D on protection to mycobacterium infections. The vitamin D mediated induction of microbicide factors against bacterial infections runs in parallel with the vitamin D immunosuppressant activity induced to control the exacerbation of the cellular immune response. These complementary effects can be modulated to guarantee a correct vitamin D action. Concerning HIV infection a protective role can be expected from the vitamin D mediated microbicide activity, but no single effects can be deduced from the vitamin D immunosuppressant activity. In addition, the direct effects of vitamin D by promoting HIV replication can act as a confounding factor when trying to understand the role of vitamin D in HIV infection. In the present review we have evaluated available bibliography of vitamin D action on the immune system response crossing it with data on HIV immunopathology trying to find common pathways that can shed light on the role of vitamin D on HIV infection and disease progression to AIDS.