AbstractEmergency department mental health triage is a complex clinical task for which the evidence base is minimal. Research in the past decade has consistently identified issues associated with the accuracy and consistency of mental health triage assessment. In this study, we investigated the predictive validity of the clinical descriptors in the Victorian Emergency Department Mental Health Triage Tool. Using a naturalistic, retrospective study design, an audit of the emergency department triage database was undertaken on 12 months of continuous data for all mental health presentations (n = 1718). The main outcome measure was urgency categorization. The study findings indicate that triage nurses can accurately identify the urgency of mental health presentations using defined clinical criteria. A significant finding was that patients with acute psychotic symptoms were more likely to be triaged as high urgency (code 2); however, the Australasian Triage Scale, in use in all Australian and many international emergency departments, provides no mental health‐specific descriptors in high‐urgency categories (1 and 2).