Background: The objective of this study was to explore patient family``s evaluation of emergency department (ED) service satisfaction and to compare these with ED staff perception of patient family``s evaluation. Methods: Based on two surveys of the National Emergency Medical Center: the 2008 National Survey for Recognition and Satisfaction towards Emergency Medical Services and the 2008 Opinion Survey of Emergency Medical Service Providers, satisfaction gaps among physicians, nurses, and patient family were evaluated by Kruskal-Wallis tests and Wilcoxon-Mann-Whitney tests. Furthermore, the factors associated with satisfaction of emergency medical service were identified by ordinal logistic regression models. Results: There were statistically significant gaps among physicians, nurses, and patient family in overall satisfaction with ED visit, length of stay in ED, enough explanation, physicians/nurses kindness, and ED facilities. Age and income in the patient family model, the number of beds in hospital,job satisfaction and year of service in the physicians model, and the number of beds in hospital, job satisfaction and the number of patients per duty hour in the nurses model were statistically significant factors associated with evaluation/perception of ED service satisfaction. Conclusion: Patient satisfaction is an important indicator ofthe quality of care and service delivery in the ED. To improve and understand satisfaction in ED service, a dyadic view of the evaluation of service quality and satisfaction-that is, from the perspectives of both the patient and the emergency medical service providers-should be concerned.