The initiation of emergency care primarily depends on the decisions made by the triage nurse. Triage decisions can therefore have a profound effect on the health outcomes of patients who present for emergency care. If the National Triage Scale (NTS) was effective in providing a standardized approach to triage, a patient with a specific problem should be allocated to the same triage category, irrespective of the institution to which they present or the personnel performing the role of triage. This study examines triage nurses' level of agreement in their allocation of triage categories to patients with specific presenting problems using the NTS. Relationships between demographic characteristics of participants and triage decisions are examined and implications of any variation for triage practice and patient outcomes are explored.