Injuries are the leading cause of years of life lost and disability-adjusted life-years in Oman. Injuries pose a considerable burden to the health care system in Oman. Worldwide, Ankle injuries (AI) are some of the commonest types of injury seen in Emergency Departments (ED) and contribute to the overcrowding in the ED. The main purpose of the study was to examine the effectiveness of the ED triage nurse led application of the Ottawa Ankle Rules (OARs) towards improving healthcare outcomes of Al patients. A prospective quasi-experimental study was conducted to examine the effectiveness of the ED triage nurse-led application of the OARs towards improving the healthcare outcomes of patients with AI. The data was collected from 96 patients with Al presenting to the ED at Sultan Qaboos University Hospital and Diwan Health complex. The intervention group (n = 46) received ED nurse-led triage assessment and initiation of radiographic tests based on the OARs and the control group (n= 50) received usual ED care. Data about demographic characteristics, events leading to AI, number of radiographic tests, and patient satisfaction was collected. The patients' pain and satisfaction with ED care were measured using the numeric rating scale and brief emergency department patient' satisfaction scale, respectively. The median age of participants was 23.5 years and the majority were male (78%). The main causes of AI were football (36%), falls (31%) and twisting while walking (24%). In the intervention group, the average number of ankle x-rays requested by the ED triage nurse using OARS (1.33 + 0.47) was statistically significantly lower than the average number of ankle x-rays requested by the ED physicians (1.88 +0.40) for the control group (t=6.19; p<0.001; 95 % CI [0.37,0.72]). Implementation of the OARs by the ED triage nurse reduced the median waiting time and overall length of stay for patients with AI by 29 minutes and 97 minutes, respectively. There was no statistically significant difference in the pain level on disposal from the ED between both groups (U= 991 and p= 0.21). There was a significant difference between the two groups in their satisfaction with ED care (t= 5.60; p<0.001). In Conclusion, Implementing the OARS significantly decreased the number of unnecessary radiographic tests requested, the waiting time and overall length of stay in the ED for Al patients. Implementing the OARs significantly increased patients satisfaction with ED care, although it had no impact on Al patient's pain on discharge. Utilization of evidence based protocols and standing orders such as OARs may reduce overcrowding and improve patient outcomes in the ED. Further studies are needed to examine the effectiveness of the OARs on other healthcare outcomes of Al patients such as effectiveness of application of OARs by ED nurses and early intervention in reducing Al patients' pain and cost of care associate with Als.