Obstructive sleep apnea (OSA) is a complex disease whose etiology is multifactorial and incompletely understood. This article focuses on upper airway anatomy evaluation and the standardization of different physical findings in patients with OSA and on the possible correlation of these physical findings with the severity of the disease. All patients underwent a physical examination and polysomnography. The physical examination included tonsil size, modified Mallampati grade, neck circumference, lateral clinical craniofacial assessment and body mass index (BMI). The study group consisted of 85 patients. A statistically significant correlation between tonsil size and BMI and with the respiratory disturbance index (RDI) was detected (P = 0.004 and 0.03 respectively). Also patients with a craniofacial anomaly have a higher RDI level than the patients without this anomaly (P = 0.03). This study has identified some standardized physical findings for predicting the severity of OSA. We aim to benefit from these findings in the selection of a rational treatment modality selection for patients with OSA.