Measles virus is the most infectious transmissible agent causing human disease and has probably been responsible for the deaths of more children than any other single cause. In addition, infection with the natural virus causes many severe complications, including encephalitis, deafness and pneumonia. The introduction of live attenuated vaccines, either singly or as the measles-mumps-rubella combined vaccine, has dramatically reduced the occurrence of disease and in countries where vaccine uptake is high, indigenous disease has been virtually eliminated. Even though the current vaccines are very efficient, they do have their limitations. Children are most at risk during the first year of life and for most of this period, maternal antibodies prevent effective immunization. In addition, the current measles vaccines are relatively heat labile which causes difficulty in tropical areas. In recent years, vaccination rates in some industrial countries have been adversely affected by fears that measles vaccines are linked to inflammatory bowel diseases and autism. Although there is no conclusive evidence to support these fears, they still remain and probably contribute to poor vaccine uptake in some regions and sections of society. Although severe complications from vaccination are extremely rare, mild local reactions are more common. Consequently, in countries where measles is declining or has been eliminated, the fear of side effects of vaccination may encourage the development of vaccines that do not rely on virus replication to take effect.