Neisseria meningitidis is differentiated into 12 distinct serogroups of which A, B, C, W-135, X and Y are medically most important and represent a major health problem in one or more parts of the world. The epidemiology of N. meningitidis is unpredictable over time and across geographic regions. A sudden increase or decrease of IMD or meningococcal carriage may occur anywhere at any time. Recent epidemiological surveillance indicates an increase of serogroup Y IMD in some parts of Europe and data from various European countries are presented.