The role of the leader of a medical unit has evolved over time to expand from simply a medical role to a more managerial one. This study aimed to explore how the behavior of a hospital-based emergency department's (ED's) leader might be related to ED unit performance and ED employees' work satisfaction. One hundred and twelve hospital-based EDs in Taiwan were studied: 10 in medical centers, 32 in regional hospitals, and 70 in district hospitals. Three instruments were designed to assess leader behaviors, unit performance and employee satisfaction in these hospital-based EDs. A mail survey revealed that task-oriented leader behavior was positively related to ED unit performance. Both task- and employee-oriented leader behaviors were found to be positively related to ED nurses' work satisfaction. However, leader behaviors were not shown to be related to ED physicians' work satisfaction at a statistically significant level. Some ED organizational characteristics, however, namely departmentalization and hospital accreditation level, were found to be related to ED physicians' work satisfaction.