Abstract: Objective To explore the prevalence of hypertension in children with obstructive sleep apnea syndrome（OSAS）.Methods Ninety snoring children were enrolled and stayed in sleeping monitor unit for a night.24 h ambulatory blood pressure（ABP）monitoring and polysomnography were simultaneously carried out. The children were classified depending of Apnea Hypopnea Index（AHI≥5） as OSAS group and（AHI＜5）as control.Results The body mass Index（BMI）,oxygen desaturation index（ODI）and total sleep time＜92% （TST92 %）in OSAS subjects were significantly higher than those of control（P＜0.05）.The OSAS children had a significantly higher daytime SBP,night time SBP and DBP（P＜0.05）.The OSAS group had a higher preva- lence of hypertension than control group（49.1% vs 10.1%,P＜0.01）.Conclusion OSAS is a risk factor for hypertension in children.Most of them the BP are shown as nondippers pattern.