Objective: To assess the validity of data collected by a new injury surveillance system in metropolitan public hospital ED in Western Australia.Methods: A reference group of four experts used text descriptions recorded in the injury surveillance system to independently assign codes for intent and cause of injury for each case in the sample. These codes were then compared with the intent and cause codes which triage nurses had assigned to these cases. The level of agreement between these codes were assessed by means of descriptive statistics. Systematic coding errors were also identified and analysed.Results: Of the 419 cases with adequate text descriptions, triage nurses agreed with the reference group of experts in 91.9% (intent) and 79.2% (cause) of cases. Falls accounted for 28.6% (n = 1.20) of cases and falls code agreement was 86.7%. Self-harm accounted for 5.3% (72 = 22) of cases and self-harm code agreement was 77.3%. Systematic errors were detected in the coding of agent of injury, the underlying mechanism of injury and falls involving a mode of transport.Conclusions: The new injury surveillance system can be successfully used in ED and provides a valid mechanism for monitoring injuries. Refinements to reduce systematic coding errors might improve the validity and quality of the data. A larger sample is needed to assess the validity of the self-harm code.