The BioSense Program monitored healthcare activity in 20 DoD facilities located in Japan from March 17 through April 11, 2011. In Japan-based outpatient DoD facilities, we monitored 10 health conditions, which are associated with injuries, and possible syndromic presentations of radiation exposure, which included nausea/vomiting, diarrhea, headache, hypotension, rash, convulsion, dyspnea, dizziness and anemia. We also searched for radiation exposure-specific International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) 990, 508.0, 558.1, E926 and E926.9. There was a 2-to 5-day lag time between the time of patient visit and time when ICD-9-CM-coded final diagnoses were available. To monitor healthcare utilization for potential adverse effects associated with KI exposure in the United States, we searched ED chief complaint (CC) data from all 635 nonfederal BioSense hospitals for the following keywords indicating a KI-related visit: (1) potas*, pottas*; (2) iodine, iodide; (3) KI; (4) radiation, radeation; (5) nuclea*; (6) Japan. A given ED visit was considered a match if the content of the CC met the following keyword inclusion criteria: 1 and 2, 3, 4 and 5 or 6. Perl Regular Expressions were used to take into account upper-and lowercase letters and word boundaries. CC data were updated within 0Á2 days following the visit date.