Exploring the evidence surrounding the debate on MMR and autism.

Autism is a poorly understood condition that would appear to be on the increase. There is currently much concern about a possible link between the measles, mumps and rubella (MMR) vaccination and autism which has resulted in a substantial reduction in the uptake of MMR, putting children at risk of three significant childhood diseases. This article looks at the evidence for a link between MMR and autism, finding that while a plausible hypothesis has been constructed, there is not substantive evidence for such a link and that the quality of this evidence is, in many cases, poor. This is due, in part, to the difficulties inherent in pre- and post-licensure vaccination research. These difficulties and the importance of vaccination and parental understanding of risk are discussed.