Patients with obstructive sleep apnea mainly due to upper airway narrowing are evaluated conventionaly by polysomography. Recently, the magnetic resonace imaging has been well established in evaluating upper airway and correlating with the severity by tongue mass and the area of retropalatal airway. However, some drawbacks of MRI includes expensiveness might lead its less use. As for ultrasound which is very popularly applied in medical illness, is more convenient and money saving than MRI. We propose that ultrsound measuring the tongue volume and width of upper airway through submental area may be a alternative image for a upper airway measuring.