Regular physical activity is recognized as a non-pharmacological treatment of genetic obesity and type-II diabetes, and based on the "anti-inflammatory" effects of exercise, it has been also proposed for improving the "chronic low-grade inflammation" in metabolic syndrome (MS). The aim of the present work was to evaluate the effects of an habitual exercise program (running, 5 days/week for 35 min at 35 cm/s for 14 weeks) and of a bout of acute exercise (running, for 35 min at 35 cm/s) on MS-associated disorders in the pro-inflammatory cytokines IL-1beta and IFNgamma. The study was carried out on obese Zucker rats (fa/fa). The obese rats presented higher circulating concentrations and constitutive macrophage production (in the absence of antigenic stimulus) of IL-1beta (but not of IFNgamma). But their production of both IL-1beta and IFNgamma by lipopolysaccharide (LPS)-stimulated macrophages was lower than that of the control lean rats. Our protocol of exercise training did not modify the circulating concentration and constitutive macrophage release of either IL-1beta or IFNgamma in the obese rats, but increased the production of both cytokines by LPS-stimulated macrophages. The single bout of acute exercise only increased the release of IL-1beta by the LPS-stimulated macrophages from obese rats, in both sedentary and trained animals. The results indicated that: (1) circulating levels and constitutive production of IL-1beta by macrophages are deregulated in rats with MS, and (2) IL-1beta and IFNgamma production by macrophages in response to antigenic stimulus (LPS) is impaired in the obese animals, and this MS-associated disorder is improved by the program of habitual exercise training.