Notes: Sumario: This article explores how health care data is collected, used, and shared within and between countries. There are many benefits to having a robust health care data infrastructure: quality of care, efficiency, coordination, monitoring, etc. As the size and breadth of the data grows, though, so does the potential for its misuse. The threats to data security, individual privacy, and potential for abuse loom especially large when it comes to health data. Technological, social, and political considerations further complicate the way health care infrastructure is constructed, used, and secured. National governments and health systems have balanced these priorities in different ways, each reflecting the values of their institutions and the trust of their populations.