The purpose of this study was to examine the influence of physical activity on cytokine production in healthy older males. Twelve males (six very active, six less active) ages 65 to 74 were recruited for this study. Blood was obtained at rest and serum concentrations for MIP-I a, IL-1 ra, IL-6 and IL-10 were measured. No difference was found in MIP-la and IL-Ira concentrations between the two groups. The serum concentration of IL-6 was significantly lower (p = 0.016) in the very active group compared to the less active group. The very active group had a significantly higher (p = 0.016) concentration of IL-10 compared to the less active group. The beneficial influence of physical activity on cytokine production is clinically important because of the role of IL-6 and IL-10 in disease development in older adults. Through influencing cytokine concentrations, our results provide further insights into the role of physical activity in attenuating the effects of aging. / School of Physical Education