Purpose:To evaluate the performance of a prehospital trauma diversion system in Hong Kong,China.Methods:A retrospective analysis of prospectively collected data in the trauma registry of Queen Mary Hospital,Hong Kong from 1 January 2009 to 31 December 2013 was done.All adult patients aged 18 years or above,either primarily or secondarily diverted to Queen Mary Hospital according to the trauma patient diversion protocol,were recruited.Need for trauma center level of care was based on a consensus-based criterion standard published in 2014.Performance of the protocol in terms of overdiversion and under-diversion was determined.Results:A total of 209 patients were included for analysis.About 30％ of the patients required trauma center level of care.The most common reason was the need for vascular,neurologic,abdominal,thoracic,pelvic,spine or limb-conserving surgery within 24 h of presentation.The over-diversion rate and underdiversion rate were 69.6％ and 19.7％ respectively.Conclusion:The trauma patient diversion protocol currently in use in Hong Kong is not accurate enough.Further revision and refinement is needed.