Sports activities can affect many components and functions of the immune system. The purpose of this study is to compare the effect of sports activities on serum level of interleukin 6 and 33 on athletes. In this study, exhaustive sports activity was carried out by 30 volleyball athletes, (each group 15 people) using aerobic exercise (Bruce test) by treadmill. Blood samples were taken before, after and 2 hours after doing sports exercise. IL-33 and IL-6 serum levels of peripheral blood were measured by ELISA (Bioscience-America. For data analysis, repeated measurements and one way variance tests were used. Serum level of interleukin 6 and 33 had a significant increase after exercise than before exercise in both male and female groups (P<0.01). On the other hand the level of these two interleukins had a significant decrease after exercise than 2 hours after exercise (P<0.01). Although the level of interleukin 6 and 33 in men were higher than female after exercise but this difference was not significant (P>0.01). Physical activities had effect on the function of immune system of athletes and it seems that these activities lead to increase the serum level of interleukin 6 and 33.