Objective : This study was conducted to find the relationship between syndrome-differentiation and Sasang-constitution in chronic fatigue patients. Methods : The subjects were 72 adults with chronic fatigue who visited Dunsan Oriental Hospital of Daejeon University between March 2007 and April 2007. Their main complaint was fatigue for longer than 6 months and they did not have any physical or mental problems. We measured their fatigue degree by using Chalder fatigue scale and health habits. To evaluate relationship between syndrome-differentiation with sasang-constitution, The patients were divided into four syndrome-differentiations, such as liver and kidney asthenia of Yin, spleen and kidney deficiency of Yang, deficiency of lung and spleen qi, and deficiency of heart and spleen blood. We also diagnosed Sasang-constitution by using Questionnaire for Sasang Constitution Classification II (QSCCII). Results : Among the 72 patients, 41.4%, 34.5% and 24.1% of belonged in Soyangin, Soeumin and Taeumin respectively. Interestingly, we found a meaningful correlation between syndrome-differentiation and physiological function by Sasang-constitution. Conclusion : The result may help Oriental medicine understanding and treatment of chronic fatigue-related diseases and patients.