- Background. Measles vaccination at ages 12–15 months is a routine part of standard health care in developed countries. Nonetheless, the prevention and control of measles outbreaks remain a challenge, owing to incomplete or variable compliance with immunization programs and primary vaccine failure (approximately 5%). In Israel, vaccination coverage against measles is high, yet sero-epidemiological studies conducted in the early 1990s showed that 15% of 18-year-olds were unprotected. Methods. 1994 there was a countrywide epidemic of measles, which spread to the military. The Israel Defense Forces Medical Corps immediately launched a wide-scale vaccination campaign, targeting primarily field units and training bases, where crowded living conditions are the rule. Results. The immunization campaign led to an abrupt cessation of morbidity in the military. In the civilian sector, where no intervention was undertaken, the epidemic continued for another 4 months. Conclusions: Institutional measles outbreaks, especially in the presence of crowded conditions or high contact rates, may be effectively controlled by mass vaccination.