The mainstreaming of mental health services in Australia has significantly altered the means of access to these services. Increasingly people seeking mental health care present at general hospital emergency departments. The triage of patients in the hospital emergency department has developed as an efficient method to determine the level of urgency and provide appropriate care and treatment. However, this process has been found to be less effective for patients presenting with mental health related problems. Triage guidelines specifically tailored for mental health needs have been introduced in the attempt to overcome existing problems, however, the effectiveness of these guidelines has not been extensively tested. This report presents the findings of a research project conducted in a large metropolitan hospital in Melbourne, Australia. All presentations to the emergency department for mental health problems (n=137) were triaged using the mental health guidelines over a three-month period. The same presentations were triaged by psychiatric nurse consultants employed in the emergency department and the results compared. Significant differences were found between the two groups in the triage ranking, with emergency nurses tending to classify presentations as more urgent than their psychiatric nurse colleagues. These findings support the important role of the psychiatric nurse consultant within the emergency department and suggest that mental health education for emergency nurses is necessary if the guidelines are to be used effectively and improve outcomes for patients presenting with mental health problems.