Aging is characterized by a proinflammatory state that contributes to the onset of disability and age-related diseases. Proinflammatory cytokines play a central role in mediating cellular and physiological responses. The levels of these cytokines may reflect immune system effectiveness. Studies of the effects of aging on inflammatory response show interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-alpha) and interleukin-1beta (IL-1beta) to be important. In this review, age-related changes in inflammatory cytokines, T and NK cells, and the biology of IL-6 and TNF-alpha and their relevance to senescence are considered.