Objectives:To evaluate characteristics of dental occlusion among non-obese Saudi adult patients suffering from moderate to severe obstructive sleep apnea(OSA).Methods:Following ethical approval, a cross-sectional study was conducted at Sleep Disorders Center, King Khalid University Hospital, Riyadh, Kingdom of Saudi Arabia, between January and March 2017. Non-obese adult Saudi patients with moderate/severe OSA (apnea-hypopnea index>15) and without history of malocclusion or edentulism were included with an estimated sample size of 50. Demographic details and severity of OSA as diagnosed by polysomnography were recorded. Characteristics of dental occlusion, namely molar, canine and incisor relationship, overjet, overbite, crossbite and arch form were obtained through calibrated examiners (kappa 0.81). Descriptive statistical analysis and Chi-square test, with 95% significance level (p<0.05), were used to identify relationships between the severity of OSA and characteristics of dental occlusion.Results:A total of 51 patients (31 males, 20 females; mean age 49.45±10.35 years), were enrolled in the study. Severity of OSA was moderate in 17 patients and severe in 34 patients. Severe form of OSA was more among males (64.7%) and in patients with Class-II division-1 incisor relationship (94.1%). Neither the demographic characteristics, nor characteristics of dental occlusion showed statistically significant relationship with the severity of OSA.Conclusion:The results of the present cross-sectional study indicate that the characteristics of dental occlusion are not related to the severity of OSA among non-obese adult Saudi patients.