A measles outbreak (126 reported cases to date) has been ongoing in Greece, since January 2010, originally related to the recent outbreak in Bulgaria. Cases are mostly unvaccinated, and mainly belong to three groups: Roma population of Bulgarian nationality, Greek Roma population, and Greek non-minority population. In these population groups, 67%, 95%, and 25% of cases respectively were children aged 0-14 years. Measures were taken to raise clinical awareness, and vaccination of specific population groups was undertaken. Policies are necessary to increase routine vaccination uptake of hard-to-reach groups.