Singi-Hwan(SH) is a widely used prescription for treating kidney inflammation in Korea. However, the protec-tive effect of SH on maximal exercise performance(MEP) is not well studied. Fatigue is the physiological phenom-ena after working and exercise to improve physical strength. The purpose of this study was to evaluate the MEP effect of SH using the FST model. To study the protective effect of SH on endurance maximal exercise performance by in vivo experiment. The mouse is largely divided into three groups; Non-swimming group, saline treatment - swimming load test group and SH processing swimming group. The swimming load test group was subdivided into the swimming control group(Control) and the Singi-Hwan supply group(SH). SH was orally administered 2 weeks before FST administration. After FST, immobility time, oxygen consumption was measured by physiological test, and serum was collected for biochemical analysis. Immobility, oxygen consumption and biochemical factors were increased FST - induced MEP. Immobility time was significantly decreased in SH treatment group compared to control group. Oxygen consumption was also significantly decreased by SH treatment. The increase of lactic acid and lactate dehydrogenase after FST was inhibited by SH treatment. Consumption of energy sources(free fatty acid and triglyceride) and energy recovery were improved by SH treatment after FST. In conclusion, SH suppressed the increase of immobility time, oxygen consumption and biochemical factors after FST. All the results suggest SH might be a potentially protective ingredient for the anti-fatigue functional food. In conclusion, SH can be used as a beneficial medium to improve maximal exercise performance and the ability to protect the body from fatigue. This study indicates that SH protects mice from physical fatigue and improves exercise performance. Therefore, it has a potential for the pharmacological effect of anti-fatigue. Our study provides new sight into the protective effects of SH on the fatigue status of mice. Additional studies are needed to find the mechanism of association between each single herb.