PURPOSE: The purpose of this study was to identify the triage and length of stay of cancer patients who visited an emergency department in a cancer center. METHODS: Aretrospective descriptive study design was used. Data were collected from medical records of patients who visited an emergency room from March 7 to June 30, 2016. Data were analyzed using descriptive statistics and Kruskal-Walis tests. RESULTS: In total, 2,699 cancer patients visited the emergency room excluding cases with insufficient records. The mean age was 58.7±18.7 years, and males were 47.0% and 56.0%, respectively. In triage, 184 (6.8%) were ‘emergency’ patients, 823 (30.5%) were ‘urgent’, and 1,692 (62.7%) were the most ‘non-emergency’ patients. The average stay of length in the emergency room was 5.79±7.69 hours. CONCLUSION: These findings show that development of triage tool and communication system with staff are needed to reduce overcrowding and length of stay of the emergency department.