Obstructive sleep apnea syndrome (OSAS) is often the result of obstruction at multiple anatomic sites. A clear understanding of the obstruction sites is necessary and various tests were reported in the literature. Although Muller maneuver and drug-induced sleep endoscopy (DISE) tests are widely used, there exists controversy regarding their use. Muller test is simple to perform, but whether this maneuver reliably represents the site/sites of obstruction during normal sleep is questionable. DISE on the other hand needs general anesthesia and an operating theater with additional costs and risks. To select the patients who will benefit from surgery and the type of surgery that would be more beneficial for the patient, and to have a common language, Friedman suggested two grading systems, addressing the tongue positioning and lingual tonsil hypertrophy.