Between 1 September 2008 and 9 March 2009, 150 cases of hepatitis A were reported in Barcelona representing a threefold increase compared with the same period in previous two years. The majority of the cases occurred in adult men, including 87 who reported having sex with men. This indicated the possibility of an outbreak ongoing in the population of men who have sex with men (MSM) and emphasised the need to target this community with more effective vaccination programmes.