Introduction: Hospital emergencies are of particular importance as they are considered as the first-line treatment for patients. Patient mortality in the emergency department is considered to be a problem as it has intensified in recent years. The aim of this study was to investigate the causes of mortality in patients admitted to the Emergency Department of Imam Khomeini Hospital in Urmia in the first half of 2017. Materials and Methods: In this cross-sectional descriptive study, after obtaining permission, the medical file of all those patients who had referred to the emergency department during the period of April 1st to September 31st, 2017 and who had died in the emergency for any reason was gathered. Data were collected from the archive and were collected for variables such as age, sex, marital status, residence, initial complaint, length of hospital stay, visitation service, and place of death and cause of death. Results: A total of 133 cases were studied, of which 77 (57. 9%) were male, 114 (85. 7%) were married and 71 (53. 4%) were residents of Urmia and the mean age of patients was 66/8± 18/9. The most common complaints reported by patients or their companions were about consciousness loss and the least reported were chest pain, hematuria, and lower extremity swelling, respectively. A high percentage of mortality (58. 6%) had occurred in patients who had been in the emergency department for 24 hours or less. The most common causes of mortality were cardiopulmonary deaths and cardiovascular disease, and ultimately in the evaluation of the duration of the disease (acute or chronic), 38 (28. 6%) had acute disorder and 95 (71. 4%) had a previous chronic disease. Conclusion: According to the results of the present study, most of the causes of mortality included cardiopulmonary arrest and cardiovascular problems. These findings reveal the importance of controlling and preventing these diseases and on the other hand, shows the necessity of proper planning, staff training and equipping the emergency departments in order to reduce mortality rates.