Abstract. This study evaluates the clinical usefulness of commonly used screening instruments for the early identification of obstructive sleep apnea. The study compared the STOP-BANG questionnaire and the Epworth Sleepiness Scale in patients with suspected obstructive sleep apnea. The assessment focused on clinical symptoms, daytime sleepiness, and objective sleep-related parameters. The findings showed that higher screening scores were associated with a greater frequency of sleep-related breathing disturbances. The STOP-BANG questionnaire provided information about the overall risk of obstructive sleep apnea, while the Epworth Sleepiness Scale mainly reflected the level of daytime sleepiness. The results indicate that these screening instruments can be useful for identifying patients who require further objective sleep assessment. However, screening questionnaires should be considered preliminary assessment tools and should be interpreted together with clinical examination and objective diagnostic methods.