Public mental health systems have been called on to better meet the needs of consumers presenting to health services with the police, yet few studies have examined police presentations among mental health consumers in large public mental health systems. This study was designed to determine the frequency profile and characteristics of consumers of mental health services brought in by police to an emergency department (ED) in Sydney, Australia. Using data from the emergency department information system and obtaining the psychiatric assessment from the medical record, we have examined trends and characteristics in mental health presentations brought in by the police to a general ED between 2003 and 2005. The sample consisted of 542 consumers with a mental health problem brought in by the police to the ED of a 350-bed community hospital. The characteristics of this group were compared with those of all mental health related ED presentations for the same period using logistic regression. Results indicated that police presentations are likely to be young males who are unemployed, have past and present alcohol and other drugs use, present after hours, and are admitted to hospital as a result of their presentation. These consumers are likely to have a presenting problem of a psychotic disorder, less likely to have a presenting problem of depression and/or anxiety, and given a triage code of three or higher. The study results highlight the importance of the availability of 24-hour access to mental health care to ensure a quick care delivery response. Police presentations to EDs with mental health issues are an indicator of significant impact on health services, especially with the current overcrowding of EDs and the associated long waiting times. Systems need to be developed that facilitate collaboration between EDs, hospital security, police services, mental health, and ambulance services.