Objective: To evaluate the role of dental parameters that may contribute in increasing apneic activity in patients with obstructive sleep apnea syndrome (OSAS). Method and materials: A total of 152 subjects (121 males and 31 females ) were examined from October 1999 until September 2001, for sleep disorder symptoms. All patients underwent polysomnography. Any abnormal or unusual features that could inhibit the upper airway of the oral cavity were evaluated by an oral pathologist. Results: Statistical analysis of the independent structural variables and the respiratory disturbance index proved to be significant only in the cases of retropositioned or narrow hard palate with a vertically positioned soft palate, the type of breathing (oral breathing), and the enlarged uvula. Conclusion: The oral soft tissues seem to be more closely associated with OSAS. Therefore, the diagnosis of the structural features of the oral cavity by the clinician is useful to predict apneic activity. Keywords: breathing, mandible, maxilla, oral cavity, sleep apnea, uvula