목적: Obstructive hypoventilation (OH) in children is defined as CO2 is increased to more than 50 mmHg for more than 25% of total sleep time. In this study, we reveal the prevalence and clinical feature of OH in children. 방법:We have analysis 173 children (1 year old to 18 years old) with complained snoring, oral breathing, which were referred to Sleep Disorder Clinic of Korean University Ansan Hospital from May 2004 to December 2014. They have underwent a polysomnography with end-tidal CO2 monitoring to diagnose the sleep related breathing disorders. 결과:In children, the prevalence of OH was 3.5% (6/173). In addition, subjects with obstructive sleep apnea (OSA) [Apnea-Hypopnea index, AHI > 1] was 62.4% (108/173). There is no significant difference between OSA group (2/65, 3.1%) and non-OSA group (4/108, 3.7%) in the prevalence of OH. The clinical feature of OH group is not significantly different from non-OH group. 결론:We found out that the prevalence of obstructive hypoventilation in children is to be not significantly different between OSA and non-OSA group. We suggest that the clinical implication of OH will be studied with larger population in future.