The purpose of the study was to investigate the change of blood acid-base eqilibrum and concentration of blood gas during 3th round Matches. Ten varsity Kwon Do players were the subjects. The Pco₂ in venous blood was significantly increased in accordance with succeeding round(p<.001). Magnitude of the increase after 2th round was higher than after land 3round. The Po₂ and O₂ SAT increased in accordance with succeeding round and was significantly increased after 2round(p<.001). The concentration of bicarbonate and pH was significantly decreased(p<.001) after 2 round. It was suggest that metabolic acidosis was induced after 2round.