Background Obstructive sleep apnea affects up to 2.9% of children. This study was to determine demographic and clinical characteristics of a group of children with obstructive sleep apnea syndrome (OSAS) as defined by sleep polysomnography (PSG) Methods A prospective study was conducted in a public-funded general hospital in Hong Kong of China Children confirmed to have OSAS by PSG were followed up between January 1997 and December 1998 Tonsillectomy and adenoidectomy (T&A) was offered to those with moderate to severe OSAS, and medication was offered to those with mild OSAS All children were followed up regularly in the sleep clinic and sleep PSG was repeated for those with marked relapse in symptoms Results Eighty-nine children (64 boys and 25 girls, mean age 7 years) were confirmed to have OSAS out of 352 children who underwent PSG during the study period The most common symptoms of OSAS were snoring (100%) and sweating (81%) during sleep and nasal blockage (61%) and sleepiness (34%) during daytime Severe OSAS occurred in 15 children Moderate OSAS occurred in 33 children Forty-one children had mild OSAS Forty-nine children underwent T&A, 5 (boys, <5 years) out of whom were found to have recurrent OSAS within 1 year Conclusion A male predominance has been found in a group of Hong Kong children with OSAS Boys undergoing T&A at an early age (<5 years) will be more likely to develop repeated OSAS Background Obstructive sleep apnea affects up to 2.9% of children. This study was to determine demographic and clinical characteristics of a group of children with obstructive sleep apnea syndrome (OSAS) as defined by sleep polysomnography (PSG) Methods A prospective study was conducted in a public-funded general hospital in Hong Kong of China Children confirmed to have OSAS by PSG were followed up between January 1997 and December 1998 Tonsillectomy and adenoidectomy (T & A) was offered to those with moderate to severe OSAS, and Services were offered to those with mild OSAS All children were followed up regularly in the sleep clinic and sleep PSG was repeated for those with marked relapse in symptoms Results Eighty-nine children (64 boys and 25 girls, mean age 7 years) were confirmed to have OSAS out of 352 children who underwent PSG during the study period The most common symptoms of OSAS were snoring (100%) and sweating (81%) during sleep and nasal blockage (61%) and sl 5 (boys, <5 years) out of whom were found to have recurrent OSAS (34%) during daytime Severe OSAS occurred in 15 children Moderate OSAS occurred in 33 children Forty-one children had mild OSAS Forty-nine children underwent TAS within 1 year Conclusion A male predominance has been found in a group of Hong Kong children with OSAS Boys undergoing T & A at an early age (<5 years) will be more likely to develop repeated OSAS