Objective: To compile the drug purchase price index and volume index, this is applied to present the dynamic changes of prices and volumes and to reflect overall supply of western medicines in Shanghai. Methods: The drug procurement re- cords of the city’s medical institutions for the 48 months during 2018 and 2021 in the Shanghai Pharmaceutical Procurement Service and Supervision Information System were included as the data basis for the index measurement. Results: Compared with the previous year, the purchase price indexes of western medicines were 93.3, 95.8 and 93.9 respectively in 2019, 2020 and 2021. Prices of west- ern medicines maintained a mild and steady downward in overall trend; the annual purchase volume had an upward trend. The price changes of drugs included in medical insurance were similar, among which the prices of cardiovascular drugs, anti-tumor drugs and immunomodulators dropped more than other varieties. Prices of those drugs not covered by the medical insurance fell slightly. Con- clusion: The empirical case of purchase price index and volume index of western medicines in Shanghai has verified the feasibility of its application in drug price monitoring and management. It has also provided strong evidence for policy decision-making and eval- uation.