The General Agreement on Trade in Services (GATS), created under the auspices of the World Trade Organization, aims to regulate measures affecting international trade in services—including health services such as health insurance, hospital services, telemedicine, and acquisition of medical treatment abroad. The agreement has been the subject of great controversy, for it may affect the freedom with which countries can change the shape of their domestic health care systems. We explain the rationale behind the agreement and discuss its scope. We also address the major controversies surrounding the GATS and their implications for the U.S. health care system.