Background: In 1995, Taiwan has launched a national health-care system (the National Health Insurance Program, NHI) covering the use of both Western medicine (WM) and Chinese medicine (CM). This populationbased study was conducted to understand the role of CM in this dual medical system by determining the utilization patterns of CM and WM and to analyze the demographic characteristics and primary indications influencing the choice of the medical services for the development of strategies to enhance the appropriate use and reduce unnecessary use of CM.