The possibility of a causal link between the measles, mumps and rubella vaccine (MMR) and inflammatory bowel disease and autism in children has received much media attention since the concern was first raised in 1998. Rigorous reviews of the scientific evidence do not support a casual link and UK health departments continue to promote MMR vaccination. However, uptake has dropped in many parts of the UK and many parents remain concerned about the safety of the vaccine. This study aimed to explore how the risk/safety of the MMR vaccine was reported in UK newspapers and discussed among parents on an Internet discussion forum. In both arenas, an impressive range of issues were discussed. These included, the quality of the available scientific literature; the status of anecdotal evidence supplied by parents; reports of increases in autism; the severity of measles, mumps, and rubella infections; the effectiveness of MMR; and single vaccines as alternatives to MMR. It was notable that while those people who doubted the safety of MMR provided specific critiques of studies that others interpreted as demonstrating MMR safety, people who supported MMR gave no such specific critiques of studies that their opponents interpreted as demonstrating an MMR-autism link. Parents expressed a range of concerns about MMR (including, the existence of scientific research that appeared to raise questions about MMR safety) and did not appear to trust the information and attempts to reassure provided by Government agencies.