It is well known that high-intensity physical activity causes excessive oxidative stress which gives rather harmful effect on health. In recent years, the application of electrolyzed alkaline reduced water (ARW) on sport field is growing rapidly. ARW was found to be effective on inhibiting of oxidative stress generated in cells during high-intensity exercise. However, the effects of ARW on the oxidative stress induced by exhaustive exercise have not yet been elucidated clinically. Therefore, we conducted the preliminary experiment to evaluate the drinking efficacy of ARW (pH 9.5) on oxidative stress and fatigue induced by high-intensity exercise in healthy adults. The maximal graded exercise was performed through Bruce protocol using treadmill. Participants drank ARW (10 mL/kg body weight) after exercise. Oxidative stress markers such as reactive oxygen species, nitric oxide, glutathione peroxidase and malondialdehyde, as well as the fatigue markers such as lactate, lactate dehydrogenase were assayed. Our preliminary results showed that the level of oxidative stress markers were significantly decreased after ARW intake compared to the level of baseline. ARW also showed significant decrease in the level of fatigue markers. Overall, our results demonstrate that drinking ARW is effective in reducing oxidative stress and fatigue after exhaustive exercise. Therefore, ARW is expected to be useful as a healthy sports drink after an intensive physical activity.