Gastrointestinal disease is one of the most common manifestations of H
IV infection. The gastrointestinal tract contains abundant quantities
of lymphoid tissue and is Likely to function as a reservoir of HIV inf
ection, a site of profound immune dysregulation, and a target for oppo
rtunistic infection and malignancy. The purpose of this article is to
describe the mucosal immune system in health and to summarize the pert
urbations reported in association with HIV infection.