Purpose: This study was conducted to examine the relationship among task interruption, task performance, and burn-out in nurses working at emergency room. Methods: The subjects of this study were 225 working at emergency rooms of 19 hospitals. Data was collected by using the structured questionnaire, including frequency of task interruption. problems in task performance due to interruption, and burn-out. Results: The average scores of task interruption were 2.06 due to communication, 1.49 due to treatment and record, and 1.39 due to other services (range 1-4). Frequency of task interruption was significantly correlated with task performance and burn-out. Conclusion: Emergency room nurses experienced some task interruption. The task interruption can influence upon task performance and burn-out of emergency room nurse.