This audit was set up to quantify the effect of implementing the Ottawa ankle rules in a district general hospital that relies on both medical and nursing radiography requests. Data were collected prospectively on 207 patients who presented with an acute ankle injury between August 2001 and February 2002. The department's activity was recorded before and after a period of teaching on the Ottawa ankle rules. Before teaching, 71% of patients with an acute ankle injury were sent for radiography; teaching reduced this figure to 56% (p<0.05). Auditing the activity of our department enabled us to observe a significant decrease in the number of patients sent for ankle radiography following acute ankle injury. This correlates well with research in other settings. The difficulties of rationalising radiology investigations are discussed