PURPOSE: To improve outcome of severe trauma patient, the shortening of transport time is needed. Although helicopter emergency medical services (HEMS) is still a subject of debate, it must also be considered for trauma system. The aim of this study is to assess whether transport method (HEMS versus ground EMS) is associated with outcome among inter-hospital transport. METHODS: All trauma patients transported to regional emergency center by either HEMS or ground EMS from September 2011 to September 2014. We have classified patients according to two groups by transport method. Age younger than 15 years and self-discharged patients were excluded. RESULTS: A total of 427 patients were available for analysis during this period. 60 patients were transported by HEMS and 367 patients were transported by ground EMS. HEMS group had higher mortality than ground EMS group (23.3% vs 3.5%; p<0.001), and included more patients with excess mortality ratio adjusted injury severity score (EMR-ISS)above 25 (91.7% vs 48.8%; p<0.001). In the multivariable regression analysis, HEMS was not associated with improved outcome compared with ground EMS, but only EMR-ISS was associated with a mortality of patients (odds ratio, 1.06; 95% confidence interval, 1.04-1.09). CONCLUSION: In this study, helicopter emergency medical services transport was not associated with a decreased of mortality among the trauma patients who inter-hospital transported to the regional emergency center.