The trace element zinc is involved in many important immune processes. A number of immunologic impairments owing to zinc deficiency are also evident in HIV disease, most notably a reduction in the number of circulating T lymphocytes. Observational epidemiologic studies have provided conflicting results on the role of zinc status in HIV disease progression. Randomized, placebo-controlled trials are needed to resolve this controversy. Studies must also address the role of zinc in vertical transmission of HIV from mother to child and its role in reducing the risk of adverse pregnancy outcomes, both of which are of considerable public health importance in developing countries.