BACKGROUND Volleyball is briefly described as an "interval" sport with both aerobic and anaerobic components. Exercise may influence antioxidant/prooxidant balance, which leads to differences in oxidative stress status between athletes in different sport disciplines, but the results of the previous studies are inconsistent. In this study, we aimed to determine the acute effects of exercise on oxidative stress parameters such as serum total oxidant status (TOS) and total antioxidant status (TAS) levels in volleyball players. METHODS Thirteen male volleyball players from the same team participated in this study. The volleyball game lasted approximately 95 minutes including warm-up and cool-down periods. Blood samples were taken before the warm-up and after the cool down. Serum TOS and TAS levels were measured. Oxidative stress index (OSI), a predictor of antioxidant/prooxidant balance (TOS/TAS), was also calculated. RESULTS The following data were revealed as median: TOS 6.84 μmol H2 O2 Eq/L(95% CI: 5.80-8.13) and 5.15 (95% CI: 4.20-6.02); TAS 1.96 mmol Trolox Eq/L(95% CI: 1.91-2.08) and 1.95 (95% CI: 1.86-2.00); and OSIindexes, 3.31 (arbitrary unit) (95% CI: 2.84-4.00) and 2.64 (95% CI: 2.26-3.18) before and after the match with respectively. Serum TOS and OSI levels were significantly lower after volleyball match when compared to before (P<0.05). There was no significant difference in serum TAS levels (P>0.05). CONCLUSIONS In individuals who exercise active sports, TOS level has been found to be decreased while TAS level has not been affected significantly after volleyball match. Our results suggested that volleyball training may not cause oxidative stress in these players. Regular physi-cal exercise especially, volleyball training may provide adequate protection against exercise-induced oxidative stress.