Twenty-seven (73%) of the 37 cases were imported*; 14 (52%) cases occurred in U.S. residents who acquired measles while traveling abroad, and 13 (48%) occurred in foreign nationals who acquired disease abroad and traveled to the United States. The countries from which measles was imported were China (13 cases), India (four), Bangladesh (two), and Thailand (two), with six other countries contributing one case each (Malaysia, Nigeria, Philippines, Russia, Saudi Arabia, and the United Kingdom). Of the 27 persons with imported measles cases, 13 (48%) were infectious during aircraft flights (i.e., rash onset occurred within 4 days before through 4 days after the date of arrival). One case of transmission after exposure on an aircraft flight was documented in a passenger who had been vaccinated with 2 doses of measles-containing vaccine and who was seated next to a person with infectious disease. All 14 U.S. residents with imported cases were eligible for measles vaccination, according to recommendations from the Advisory Committee on Immunization Practices.3 Of these, nine (64%) were unvaccinated, three (21%) had unknown vaccination status, and two (14%) had been vaccinated with ≥1 dose of measles-containing vaccine. Of the 13 imported cases among non-U.S. residents, 10 (77%) were in unvaccinated persons and three (23%) were in persons with unknown vaccination status.