To evaluate the accuracy of STOP-Bang (SBQ) questionnaire in the screening of patients with obstructive sleep apnea (OSA). The data were collected from September, 2011 to May, 2012 at the Sleep Medicine Center of West China Hospital, Sichuan University. A total of 350 consecutive patients (302 males and 48 females, 19-68 years old, average (42.9±11.0) years old) with suspected OSA who underwent an overnight polysomnography (PSG) were recruited into this study. SBQ questionnaire was completed. Based on the severity of OSA which were determined by apnea-hypopnea index (AHI), the patients were classified into four groups of primary snoring (<5 events/h), mild (5-14 events/h), moderate (15-29 events/h) and severe OSA (≥30 events/h). To evaluate the accuracy of SBQ, sensitivity, specificity, positive predictive values, negative predictive values and the area under the receiver operating characteristics curve of SBQ questionnaire were calculated. Of the subjects, 322 (92.0%) were classified as high risk based on th