From 1 January to 14 April 2011, a total of 155 measles cases were notified in Belgium, whereas throughout 2010, there were only 40. Of the 103 cases with known vaccination status, 87% had not been vaccinated with measles-mumps-rubella vaccine. The resurgence of measles is the consequence of insufficient vaccine coverage in previous years. Efforts to communicate the benefits of measles vaccination to the public and to advise health professionals on control measures and outbreak management are ongoing.