Background: The aim of this study was to compare the patterns of obstructive sleep apnea (OSA) among obese and non-obese Korean adults, usingclinical and polysomnographic data obtained for a polysomnographic study. Methods: A retrospective descriptive study was conducted by analyzing polysomnographic data collected from 86 consecutive patients whounderwent a polysomnogram from January 2011 to December 2012. Of the 86 subjects, 69 were diagnosed with OSA (apnea-hypopnea index [AHI]≥5). These patients were categorized into the non-obese/wide oropharynx group (group W), non-obese/narrow oropharynx group (group N), andobese group (group O), based on body mass index (BMI) and otorhinolaryngological findings. Results: There was no significantly different parameter among the three groups, although group O showed the highest AHI, followed by group W andby group N. Mean SaO2 was lower in group W and O than in group N, but not significantly. Although central apnea was more common in group Nand O than in group W, there was no significant difference in the number of episodes of central apnea among the three groups. Conclusion: Based on AHI and SaO2, this study demonstrated that the OSA of group O was the most severe, followed by group W and group N. Eventhough obesity was still important for OSA severity, this study also suggested that there might be pathogenic factors other than reduced upperairway in non-obese patients with OSA.