Objectives It has been proved by many researchers that there are different dominant narrowing site of upper airway according to age and many sleep parameters change with age. We evaluate the difference of physical examination and severity of obstructive sleep apnea according to age. Methods 255 male patients were subjected to this study. All of them were diagnosed OSAS by polysomnography and examined preoperative work-up including BMI, cephalometry parameter(PAS, PNS-P, MPH), nasopharyngoscopy with Muller maneuver before surgical treatment. We measured sleep parameters (lowest oxygen saturation, Apnea-hypopnea index) by polysomnography and studied the difference of physical exam and sleep parameter among the 4 groups (-29,30–39, 40-,50-) according to age. Results Among the estimated parameters of 4 groups which were divided according to age, there were significant difference in BMI, neck circumference, chest circumference, abdominal circumference in physical exam and PNS-P, MPH in radiologic finding. (p<0.05) AHI that reflects OSA severity was significantly different among 4 groups. Patient distribution of over 15 AHI score were 36% in the under 29 group, 72% in 30–39 group, 59% in 40–49 group and 55% in the over 50-years-old group. Conclusions According to the ages, we found that physical exam, and radiologic finding were different significantly among age groups. AHI were significantly different among 4 groups and OSA severity was increased significantly after 30 years old, but there was no difference significantly in the over-30 groups.