OBJECTIVES: To analyze the market situation of extremely low-priced drugs with the National Health Insurance in Taiwan. METHODS: The analysis was limited to the ambulatory setting. The data sources came from the claims datasets of prescriptions dispensed at contracted pharmacies (GO, complete) and at hospitals and clinics (OO, 1/500 sampling) in 2007, offered by the National Health Insurance Research Database in Taiwan. For favorable comparisons, the focus was on oral drugs with solid forms, e.g. tablets and capsules. A cheap drug was defined as with a unit price