Introduction: Obstructive sleep apnea syndrome (OSAS) is a common disease associated with significant morbidity, including excessive daytime sleepiness, cardiovascular disease and stroke. Method: We studied prospectively the patients sent to our sleep laboratory for polysomnography (PSG) during 6 months. One-hundred patients were interviewed with a sleep questionnaire, 3 of them were ruled out because the lacking of PSG and 2 who no completed the Epworth sleep scale (ESS). Results: Out of the 95 patients, there were 85 men and 10 women, with a mean age of 47.4 ± 12.5 years, obesity was found in 42.5%, an ESS greater than 11 points was found in 56.8%, loud snoring in 93.7%, breathing cessation in 68.4%, excessive daytime somnolence in 57.9%. PSG revealed no OSAS in 14.7%, slight OSAS in 27.4%, moderate OSAS in 21% y severe OSAS in 36.8%. Body mass index and breathing cessation reported by the couple had the highest discriminative power with a sensibility of 87% and specificity of 50% for ruled out severe OSAS. Conclusion: A severe OSAS is less probable when there is absence of breathing cessation during sleep reported by the couple and an IMC <30 Kg/m².