Open ankle fractures present a significant clinical challenge. The management and outcome of these injuries has been extensively reported, but there have been no reports of the epidemiology and how this has changed over time. We report 178 adult patients with open ankle fractures presenting to our unit over a twenty-three year period. The study centre is the only hospital receiving adult orthopaedic trauma in the region and has a defined population. The incidence of open ankle fractures was 1.5/10(5)/year, representing 1.5% of all ankle fractures. The mean age was 55years (range 16-96), with the highest incidence occurring in women over the age of 90. The most common mechanism was a simple fall with only 26% of cases due to a motor vehicle collision (MVC). 82% of cases were isolated injuries. Social deprivation had no significant influence on the incidence, but there was a difference in the mechanism with the majority of injuries in the most deprived quintile caused by MVCs and significantly fewer due to simple falls (p=0.047). Over the twenty-three years, there was a significant increase in the mean age from 44 to 64years (p=0.03). The overall incidence remained constant over the two decades. In common with many traumatic injuries, open ankle fractures are increasingly low-energy insufficiency fractures affecting elderly patients, particularly older women. This has implications for service planning and training as well as the surgical intervention in these patients.