Measles, mumps, rubella (MMR) vaccine is a live vaccine preparation containing attenuated strains of all 3 viruses. MMR vaccine is widely used throughout the world, with the US having the widest experience with the vaccine. In countries where the vaccine has been introduced successfully, significant reductions in all 3 diseases for which it is protective have occurred. The vaccine has been shown to be highly immunogenic, with seroconversion rates of 95 to 100% being achieved for each of the 3 component vaccines. This immunity appears to be long-lasting and may even be lifelong. Minor adverse effects may occur approximately 1 week after immunisation. Rarely, mumps vaccine-induced meningitis (milder than that associated with wild mumps virus) may occur, its frequency varying with the strain of attenuated mumps virus contained in any particular vaccine. Clinically, the vaccine is indicated for infants aged between 12 and 15 months, and should be administered by intramuscular or deep subcutaneous injection. A few specific contraindications exist, including a genuine hypersensitivity to eggs, and to the aminoglycoside antibiotics kanamycin and neomycin. An increasing number of countries are now adopting a 2-stage MMR policy in an attempt to prevent epidemics among those who remain unprotected, and to move towards eventual disease eradication.