The STO-BANG questionnaire, S standing for snore, T tired, O observed apneas, P pressure (arterial hypertension), B BMI (body mass index> 35 kg/m2), A age (> 50 years old), N neck circumference (> 40 cm), G gender (male); is a simple tool that enables the detection of patients with obstructive sleep apnea syndrome (OSA). If the patient adds 3 or more points, it is considered to have a high probability of having this disease. Our goal was to evaluate the capacity of the STOP-BANG questionnaire and to compare it with the ability of a sleep trained pulmonologist in determining the probability of OSA. A retrospective analysis of 327 patients suspected of having this condition was performed. One hundred and seventy-one were males (52.3%), 49.8 years old (37.9-61.7), BMI 38.7 kg/m2 (32.5-46), neck circumference 44 cm (41-47.5), 311 snorers (95.1%), 232 with daytime sleepiness or usual tiredness (70.9%), 206 with observed apneas (63%), 169 with arterial hypertension (51.7%), normal polysomnography 42 (12.9%), mild 65 (19.9%), moderate 59 (18%), severe 161 (49.2%). The STOP-BANG's sensibility and specificity, taking as a cut-off point a respiratory disturbance index (RDI)> or= to 15, was 99.1% and 14.0% respectively, area under curve (AUC) 0.755 (0.704-0.800), the values for the PR actioner's ability were 89.1% and 58.9% respectively, AUC 0.550 (0.542-0.638). The STOP-BANG questionnaire is easy to implement as a screening tool.