ObjectiveTo assess the fatigue in patients with obstructive sleep apnea hypopnea syndrome (OSAHS), and analyze the factors caused fatigue and the relationship between quality of life (QOL) and fatigue. MethodsOne hundred and sixty-nine patients with OSAHS and 78 subjects without OSAHS diagnosed by polysomnography (PSG) between December 2010 and March 2011 in West China Hospital were recruited in the study. Fatigue was assessed by using multidimensional fatigue inventory (MFI), excessive daytime sleepiness by Epworth sleepiness scale(ESS), QOL by functional outcomes of sleep questionnaire (FOSQ). ResultsFatigue in the patients with OSAHS was more severe than that of the controls (51.06±13.39 vs. 44.82±9.81, P < 0.001), but no difference was revealed in the patients with different degree of OSAHS. Fatigue was positively correlated with ESS score(r=0.210), total sleep time intervals(r=0.156), and the ratio of time of SpO2 below 90% in total sleep time(r=0.153)(P < 0.05), and was negatively correlated with the average oxygen saturation(r=-0.171, P < 0.05) and all subscales of FOSQ(P < 0.01). ConclusionsFatigue in patients with OSAHS is more severe than that of controls. Fatigue can significantly reduce QOL, and the impact is greater than that of excessive daytime sleepiness.