The complex relationship between immunity and the insulin resistance syndrome is likely mediated to a significant degree by cytokines and the inflammatory proteins they induce. Epidemiologic work has revealed associations between cytokines and clinically evident insulin resistance, and mechanistic studies have yielded insight into the induction of insulin resistance at the cellular level by cytokines such as tumor necrosis factor-alpha. Genetic polymorphisms significantly influence this relationship, and variations in cellular immunity as manifested by T-helper cell phenotype are likely to be important as well. Further elucidation of the link between immunity and insulin resistance may lead to more effective treatment, and potentially prevention, of the insulin resistance syndrome.