OBJECTIVES: The aim of our study was to assess the HRQOL recovery of trauma patients at 12 months after injury using the Short Form (SF-36) Health Survey and identify predictive factors associated with improved mental health (MH) and physical function (PF) over time. METHODS: A prospective cohort study was performed in our tertiary care hospital from September 2013 to September 2015. All consecutive trauma patients who were admitted to our department were included except for those under the age of 18, or with coexisting cognitive impairment, or deceased. Data were collected prior to hospital discharge and 3,6, and 12 months post injury. Data included SF-36, injury characteristics, acute care factors and social status. Linear mixed-effects models were used to identify factors associated with MH and PF in SF-36. RESULTS: Complete data collection was achieved in 129 out of 185 patients. The median age was 66 years (interquartile range: 54 to 75), and 82 (64%) were male.Seven of the eight SF-36 domains except Genaral health improved significantly over 12 months, however all domain scores were lower than Japanese standard norms. Never married status was associated with better MH. On the other hand, head injury (AIS≧3) were predictive of lower MH over the 12 months of follow-up. Independence at home was associated with better PF. On the other hand, lower-extrimity injury (AIS≧3) was predictive of lower PF. However, ISS and the mechanism of injury were not predictive factors associated with both MH and PF. CONCLUSIONS: All domain scores were lower than Japanese standard norms at 12 months after injury, however most SF-36 domains improved significantly over 12 months. Social status and localization of injured body region affected more strognly the long-term HRQOL than ISS. With regard to localization of injured body region, head injury affected negatively MH and lower-extrimity injury affected negatively PH.