Objective: To examine trends in mechanism and outcome of major traumatic injury in adults since the implementation of the New South Wales trauma monitoring program, and to identify factors associated with mortality. Design and setting: Retrospective review of NSW Trauma Registry data from 1 January 2003 to 31 December 2007, including patient demographics, year of injury, and level of trauma centre where definitive treatment was provided. Participants: 9769 people aged ≥ 15 years hospitalised for trauma, with an injury severity score (ISS) > 15. Main outcome measures: The NSW Trauma Registry outcome measures included were overall hospital length of stay, length of stay in an intensive care unit and inhospital mortality. Results: There was a decreasing trend in severe trauma presentations in the age group 16-34 years, and an increasing trend in presentations of older people, particularly those aged ≥ 75 years. Road trauma and falls were consistently the commonest injury mechanisms. There were 1328 inhospital deaths (13.6%). Year of injury, level of trauma centre, ISS, head/neck injury and age were all independent predictors of mortality. The odds of mortality was significantly higher among patients receiving definitive care at regional trauma centres compared with Level I centres (odds ratio, 1.34; 95% CI, 1.10-1.63). Conclusions: Deaths from major trauma in NSW trauma centres have declined since 2003, and definitive care at a Level 1 trauma centre was associated with a survival benefit. More comprehensive trauma data collection with timely analysis will improve injury surveillance and better inform health policy in NSW.