Aim This study aimed to determine factors linked to hypothermia (<35 é in Queensland trauma patients. The relationship of hypothermia with mortality, admission to intensive care and hospital length of stay was also explored. Methods A retrospective analysis of data from the Queensland Trauma Registry was undertaken, and included all patients admitted to hospital for =24 h during 2003 and 2004 with an injury severity score (ISS) > 15. Demographic, injury, environmental, care and clinical status factors were considered. Results A total of 2182 patients were included; 124 (5.7%) had hypothermia on admission to the definitive care hospital, while a further 156 (7.1%) developed hypothermia during hospitalisation. Factors associated with hypothermia on admission included winter, direct admission to a definitive care hospital, an ISS = 40, a Glasgow Coma Scale of 3 or ventilated and sedated, and hypotension on admission. Hypothermia on admission to the definitive care hospital was an independent predictor of mortality (odds ratio [OR] = 4.05; 95% confidence interval [CI] 2.26-7.24) and hospital length of stay (incidence rate ratio [IRR] = 1.22; 95% CI 1.03-1.43). Hypothermia during definitive care hospitalisation was independently associated with mortality (OR = 2.52; 95% CI 1.52-4.17), intensive care admission (OR = 1.73; 95% CI 1.20-2.93) and hospital length of stay (IRR = 1.18; 95% CI 1.02-1.36). Conclusions Trauma patients in a predominantly sub-tropical climate are at risk of accidental and endogenous hypothermia, with associated higher mortality and care requirements. Prevention of hypothermia is important for all severely injured patients.