Purpose: This paper provides a summary of the issues associated with the emergency triage of clients who have a mental illness in order to demonstrate the complexity inherent in contempory emergency triage practice to this client group. Procedures: A review and analysis of English language peer reviewed literature and research was undertaken. Findings: Since 1993 there have been a range of initiatives implemented in Australian emergency departments that were aimed at improving the assessment and management of clients presenting with a mental illness. The assessment and subsequent response for clients presenting with a mental illness are highly variable. Currently the terminology related to mental health emergency triage is poorly defined. Many improvements in mental health service delivery have been acknowledged as beneficial to staff and clients in emergency departments. Despite this there remains a dearth of literature about mental health services operating within the specific time constructs as prescribed by the Australasian Triage Scale. Recent research suggests that the mental health descriptors within the Australasian Triage Scale may not be a reliable tool for accurate mental health triage assessment. Principle conclusions: These assertions suggest there is an imperative for further research into the practices and processes that underpin the emergency triage of, and response to, clients who have a mental illness and who present to an emergency department.