In Turkey, all heavy-vehicle driver's license applicants older than 45 years and with body mass index (BMI) >25 kg/m2 are required to have polysomnography (PSG). However, this law is usually overlooked in practice due to the large number of applications. We aimed to assess the usefulness of four standardized questionnaires: Berlin, STOP, STOP-BANG and OSA50, in identifying the high-risk bus drivers for obstructive sleep apnea (OSA). Ninety highway bus drivers underwent polysomnography and completed four questionnaires. They also underwent otolaryngologic evaluation and blood testing for probable co-existing conditions such as diabetes and hypothyroidism. Neck circumference, BMI, waist circumference, prevalence of OSA and metabolic syndrome, oxygen desaturation index and duration of sleep associated with less than 90% saturation were significantly higher and mean oxygen saturation was significantly lower in drivers >45 years old than drivers <45 years old. STOP-BANG questionnaire had the highest sensitivity (87%) and the highest negative predictive value (NPV) (76%) in identifying high-risk for OSA. A cut off of 45 years old is suitable in screening highway bus drivers for OSA. Among the four questionnaires, STOP-BANG questionnaire had the highest sensitivity and negative predictive value (NPV) in identifying high risk patients for OSA in highway bus drivers and can be safely used as a screening test in this group.