We will test this by comparing serum levels of vitamin D metabolites and indices of mineral metabolism (25(OH)D 1,25(OH)2D) and PTH) in HIV-infected children and adolescents receiving HAART compared to healthy controls. Data for testing this will be obtained from the cross-sectional study. The HIV-infected group will consist of a sample of HIV+ children screened for recruitment into the study while the healthy group will consist of similar aged children recruited from the same neighborhood (including healthy siblings of the HIV positive children). Screening levels of serum vitamin D metabolites and PTH in the HIV-positive children will be compared with levels in the healthy children using an independent samples t-test.