We do not anticipate Vitamin D3 will have an adverse effect on HIV infection or antiretroviral medications. However, HIV-infected subjects who experience an otherwise unexplained decline in immune status, based on CD4 count or CD4%, or an increase in measure of HIV viral load believed by the treating physician to be possibly related to study medications will be withdrawn from study participation. Measurements of CD4 count, CD%, and HIV viral load will be measured at the clinical care sites as per standard of care. Results will be monitored by the treating physician.