OBJECTIVE: To investigate the common causes of unexplained syncope in children. METHODS: A total of 434 children with unexplained syncope who were aged from 3.0 to 17.9 years (192 males and 242 females) and who saw the doctor between January 2006 and October 2011. were examined in order to explore the detailed histories and causes of syncope and to analyze variance in causes among different ages, genders, syncope frequencies and head-up tilt test (HUTT) results. RESULTS: (1) The causes of occasional syncope included persistent standing (30%), movement (13%), change in body position(9%), sitting(7%), and playing(6%). Persistent standing was more common as a cause in females than in males (P<0.01). Micturition syncope was mainly seen in males. Sultry weather was the main cause of syncope in females. Change in body position was a more common cause in the ≥12 years group than in the <12 years group (P<0.05), while other causes showed no significant differences among different age groups. Change in body position was a more common cause of syncope in children with negative HUTT results than in those with positive HUTT results (P<0.05). (2) All causes of occasional syncope can induce repeated syncope, and most repeated syncope (56%) had the same cause. CONCLUSIONS: The common causes of unexplained syncope include persistent standing, movement and changes of body position in children. Avoiding these causes is helpful for prevention of childhood syncope.