Objective: To describe mortality pattern and to deter-mine undiagnosed fatal injuries according to autopsy find-ings among road traffic accident victims in Yazd, Iran. Methods: In this retrospective study, 251 victims of road traffic accidents who were admitted to a tertiary trauma hospital over a two-year period (2006 and 2007) and received medical cares were included. Hospital records were reviewed to gather demographic characteristics, road user type, and medical data. Autopsy records were also reviewed to determine actual causes of death and possible undiagnosed injuries occurred in the initial assessment of the emergency unit or during hospitalization. Results: There were 202 males (80.5%) and 49 females (19.5%). The mean (±SD) age of fatalities was 34.1 (±21.5) years. Pedestrian-vehicle accidents were the most common cause of trauma (100 cases, 39.8%). The most common cause of death was central nervous system injury ( 146 cases, 58.1%). The other causes were skull base fractures (10%), internal bleeding (8%), lower limb hemorrhage (8%), skull vault fractures (4%), cervical spinal cord injury (3.6%), airway com-promise (3.2%), and multifactor cases (5.1%), respectively.Thirtysix fatal injuries in 30 victims (12%) mainly contributed to death according to autopsy, but were not diagnosed in initial assessments. The head (72.2%) and cervical spine (13.8%) regions were the two most common sites for undiagnosed injuries. Conclusion: Training courses for emergency unit medical staff with regard to interpreting radiological findings of head and neck and high clinical suspicion for cervical spine injuries are essential to improve the quality of early hospital care and reduce the mortality and morbidity of traffic accident patients.