The aim of this study was to identify deficiencies in the timeliness of emergency care received by patients with open fracture of the lower limb treated in the Accident and Emergency department at the City Hospital Truro, to help decide whether further investments in emergency ambulance services are warranted and, if so, where specific investments should be made. The ambulance service 'response time', 'on-scene times' and 'mission times', and the 'time to operation after attendance in casualty' were considered. The major deficiency in care identified was the long in-hospital delay before operation, probably resulting from unavailability of operating theatre staff. A lesser deficiency was that ambulance crew seemed to be spending too long on-scene. Suggestions are made on how to identify weaknesses in emergency service, and thus prevent costly and inappropriate investments.