The objective of the Clinical Core (Core C) is to provide biologic specimens and corresponding clinical and laboratory data from well-characterized patients with HIV infection and kidney disease and from relevant controls to support the work proposed in this Program Project. The Clinical Core will provide kidney tissue, urine, blood, and stool specimens to support research into the long-term consequences of chronic HIV infection in the kidney, including the role of HIV infection in promoting kidney disease and the potential for the kidney to serve as a reservoir for the virus.