Objectives This study compared the demographic and clinical characteristics of police referrals with referrals from other sources to a psychiatric emergency department. Methods A retrospective cross-sectional study was conducted on the data from the psychiatric emergency department of Ulsan University Hospital from January 2014 to October 2017. The study sample consisted of 79 psychiatric patients who were referred by police, and the characteristics of this group were compared with those of 240 psychiatric patients who were referred by other sources. The collected data were analyzed using a chi-square, Fisher’s exact test, and independent sample t-tests Results Among the 1768 psychiatric emergency visits, 89 (5.0%) were referred by police, and among the 79 referrals by police chosen as the study group, there were 4(5.1%) cases of emergent psychiatric admission. These patients referred by police were more likely to be male and in a lower socio-economic status. Police referrals were more likely to exhibit violent behavior, be restrained, and more likely to visit after working hours. They were notified more rapidly to the psychiatric department, less notified to other departments, and visited the psychiatric outpatient clinics less after discharge from the emergency department. Conclusion The study results highlight the importance of understanding the characteristics of psychiatric emergency patients referred by police and identifying the problems of the current psychiatric emergency services. Systems need to be developed that clarify the roles of police in psychiatric emergencies and facilitate collaboration between police and mental health institutions.