Interleukin-2 (IL-2) is a secretory cytokine produced by activated T cells that stimulates T cells, B cells, and natural killer cells to proliferate and release cytokines. In addition, IL-2 slows apoptosis of HIV-infected cells. Clinical studies have demonstrated that exogenous human recombinant IL-2 can be safely administered concurrently with potent antiretroviral therapy to HIV-infected patients. It was further demonstrated that recombinant human IL-2 therapy produces sustained increases in CD4+ cell number and function in patients with both early and late HIV disease. Further evaluation of the clinical efficacy of IL-2 in HIV-infected patients is expected to provide important information on the utility of recombinant human IL-2 in HIV disease.