This research takes the family medicine department of a medical center as the subject. On-site observation of outpatient operation was conducted to explore the basic parameters and statistics that could be lent to simulation experiments. Data were collected in two periods. The first run was conducted between Dec. 19-24, 1994 for first-visit patients. The second run was conducted between Jan. 12-24, 1995 for repeated-visit patients. Simulation analysis was performed to describe the actual situation and to explore potential improvement schemes. The following alternatives were found to be helpful in improving the outpatient department's operation: (1)Setting a maximum amount of patient visits for each section. (2)Lessening the interarrival time for pre-registration patients. (3)Increasing the pre-registration rate. (4)Discouraging patients from arriving late.