This study aims to determine the prevalence and patterns of use of specific recreational drugs in all patients with injuries requiring assessment by a trauma team at the Royal Adelaide Hospital over a one-year period. It involved the identification and quantitative analysis of blood samples for the presence of ethanol, opiates, methadone, amphetamines, benzodiazepines, cannabinoids and cocaine. The results were compared with each patient's prescribed medications, thereby yielding an estimate as to the prevalence of recreational drug use in patients presenting to hospital following a trauma. The study also examined the demographics and patterns of drug use in this population, as well as the correlation between specific drug use and mechanism, pattern and severity of injury. Quantitative analysis potentially allowed inferences to be drawn on the degree of impairment of the trauma victim. The findings provide evidence of the incidence and severity of drug- and alcohol-related trauma in South Australia. Alcohol remains the most common recreational drug found in trauma patients. There is evidence to suggest that use of recreational drugs before/while driving is associated with increased risk of injury occurrence and severity. (Executive summary, edited)