Abstract： Objective To investigate breathing disorders in bus drivers and analyse the relationship between traffic accidents and drivers with sleep apnea syndrome (SAS). Methods 100 consecutive patients were recruited at random to complete overnight polysonmography and sleep questionnaires. Results 25 of the 100 were found to have SAS with an AHI of>5 (ie, averaging more than 5 such events per hour of sleep) , including 15 eases with mild SAS,7 cases with moderate SAS and 6 eases with severe SAS. There was a signicant fall in nocturnal saturation in them. Conclusion There is higher percentage of patients with SAS in automobile drivers. Sleepiness due to long-term hypoxemia at night causes daytime cognitive impairments and reaction fatigue, which is the potential reason for occurrence of traffic accidents.