We examined the prevalence of medical problems in children and teenagers with Down syndrome in Hong Kong. Methods: Children with Down syndrome receiving care from seven regional hospitals were included and their hospital records were reviewed. A total of 407 patients, aged between 0.06 and 17.16 years were included. Cardiovascular problems were observed in 216 (53%), endocrine problems in 111 (27%), gastrointestinal problems in 46 (11%), haematological problems in 18 (4%), neurological problems in 27 (7%), sleep problems in 36 (9%), skeletal problems in 56 (14%), visual problems in 195 (48%) and auditory problems in 137 (34%). Conclusions: The prevalence of medical problems was high in children and teenagers with Down syndrome in Hong Kong and similar to previous findings elsewhere. Future studies on the local prevalence of medical problems in the adult population with Down syndrome would help to define their medical needs.ticipate. Children aged below 18 years old were included in the study. Demographic data collected included the name, sex, age, date of birth and identity card number. The age of a child was taken as the date on which the latest growth parameters were recorded. Children with the same name and identity card number were considered to be duplicate cases. For children without an identity card number submitted, they were regarded as duplicate cases if they had the same name, sex, age and date of birth. Hospital records were reviewed by participating paediatricians. Relevant data was recorded according to a pre-set questionnaire (SUPPLEMENTARY FIGURE 1). The questionnaire was designed by the participating paediatricians and epidemiologist who had special interests in Down syndrome. Nine major areas (including cardiovascular, endocrine, gastrointestinal, haematological, neurological, sleep, skeletal, visual and auditory) were studied. Each area was further classified and common conditions were listed. The paediatricians were asked to review the case records and to indicate whether the child had the condition. There was a column for "other problems" in each area so that unlisted conditions might be recorded. The paediatricians were allowed to choose the "don't Around 1 in 767 babies are born with Down syndrome in Hong Kong [1] . A number of medical conditions occur more often among children with Down syndrome than among the general population [2][3][4][5] . These children need a wide range of services delivered by medical specialists, including paediatricians, general surgeons, orthopaedic surgeons, cardiothoracic surgeons, otolaryngologists and ophthalmologists.Data on the prevalence of medical problems in these children is important for optimal service planning. Previous international and local studies have investigated many issues among children with Down syndrome, including: cardiovascular [6][7][8] , endocrinology [9][10][11][12] , neurology [13][14][15] , orthopaedics [16,17] , sleep [18] and visual and auditory [19][20][21][22][23] . This study aimed to examine the prevalence of various common m...