Emergency departments are facing a worldwide problem that affects their performance, namely Overcrowding. Triage Nurse Ordering appears to be a promising approach in addition to be cost effective. This paper proposes a process-based triage nurse ordering model and assesses its efficiency on the ED performance through simulation while considering the length of stay as the key indicator. The study examines the impact of triage nurse ability, system load and triage time extension on the benefits that might be derived from triage nurse ordering.