Complete and accurate information about hospitalised injuries is essential for injury risk and outcome research, though the accuracy and reliability of hospital data for injury surveillance are often questioned. To ascertain clinical coders' views of the reasons for a lack of specificity in external cause code usage and ways to improve external cause coding, a nationwide survey of coders was conducted in Australia in 2006. Four hundred and two coders participated in the questionnaire. The results of this study show that discharge summaries and doctors' notes were the poorest source of information regarding external causes, place of injury occurrence, and activity at the time of injury. Coders viewed missing external cause information and missing documentation as having the greatest impact on the quality of external cause coding. A large majority of coders suggested that improving clinical documentation in the emergency department and introducing a centralised structured form for external cause information would improve the quality of external cause coding. Clinical coders are a valuable source of information regarding problems with, and solutions to the collection of high quality data and this research has highlighted several areas where improvements can be made and further research is needed.