The CDC's BioSense Program receives near real-time health care utilization data from a number of sources, including Department of Defense (DoD) healthcare facilities from around the globe and nonfederal hospital emergency departments (EDs) in the United States, to support all-hazards surveillance and situation awareness. Following the tsunami in Japan on March 11, 2011 , the BioSense Program modified its surveillance protocols to monitor: (1) injuries and possible radiationassociated health effects in Japan-based DoD facilities and (2) potential adverse health effects associated with the consumption of potassium iodide (KI), a salt used to prevent injury to the thyroid gland in the event of radiation exposure, among persons attending participating EDs in the US. We present the findings from that enhanced surveillance.