In Australian emergency departments the triage of people with physical illness and injury is well developed and supported by the Australasian Triage Scale. The Australasian Triage Scale contains brief descriptors of mental illness and it is unknown if these provide the same reliability in triage decision making for emergency triage nurses assessing people with a mental illness. Specialist mental health triage scales have been developed to cater for this deficit and to aid emergency staff who have lacked training in the assessment and management of people with a mental illness. A review of the development of mental health triage scales and their use in Australia identifies that using a mental health triage scale improves the competence and confidence of emergency department staff in triaging people with mental illness. Despite this there is no consistent national approach to the emergency triage of people with a mental illness. There is ad hoc use of mental health triage scales and there are few reports of improvements in service provision to this client group as a result of the use of a mental health triage scale. These findings suggest that despite the intentions of the National Mental Health Strategy a lack of equity remains in emergency departments in the provision of care to people with a mental illness who make up one in five of adult Australians. Consideration should be given to the introduction of a national approach to the use of a MHTS in Australian emergency departments.