The aim of this study was to determine the frequency of being involved in traffic accident (including near-miss accidents) when driving in subjects with obstrucyive sleep syndrome (OSAS) and those found to be simple snorers. Material and Methods: The reports of 3354 patients who had been investigated at the Gazi University Medical Faculty Sleep Disorders Center with a preliminary diagnosis of OSAS between 1994 and 2006 were evaluated retrospectively. Four hundred and thirty-one patients with OSAS and 133 subjects with simple snoring were included in the study (total 564 subjects). All subjects completed a questionnaire and the Epworth Sleepiness Scale (ESS). Each subject underwent a nocturnal polysomnographic investigation. In statistical analyses independent samples t-test, One-Way ANOVA test and chi(2) in trend test were performed. Results: OSAS and simple snorer patients showed a significant difference by gender (p< 0.001); while 78.7% of males had OSAS and 21.3% were simple snorers, the corresponding rates for females were 48.8% and 51.2%. The rate of feeling sleepy during the day was 2.8-fold higher in patients with severe OSAS than in simple snorers. Similarly, drowsiness was 3.45 times more common in this group than in simple snorers. The ESS score increased from the simple snorers to the severe OSAS cases (p< 0.001). Mild OSAS cases bad 4.35-fold and severe OSAS cases 6.59-fold increased accident risk. Conclusion: To put into practice of regulation for OSAS patients, the number of sleep laboratories must be increased.