This study aimed to understand the crude death rate of patients in the emergency department (ED) from the Taiwan national health insurance research database (NHIRD) and to determine a feasible judging process. The study materials were cohort datasets from 2000 to 2008. Analysis was done after applying particular ICD-9-CM diagnosis codes and treatment codes. The crude death rate for ED visits was 0.40%. Males accounted for 66.5% of deaths and 52.3% of patients who died were over 64 years old. The most common ICD-9- CM diagnosis was death occurring less than 24 hours from onset of symptoms not otherwise explained. The most frequently encountered proceeding emergency procedure code was endotracheal tube insertion. This paper describes data management and file merging processes that may help researchers apply cohort datasets from the Taiwan NHIRD.