Evidence published by the British Medical Journal finds no association between MMR and bowel problems or developmental regression in children.
The study carried out at London's Royal Free and University College Medical School and the Public Health Laboratory Service provides "no support for an MMR-associated 'new variant' form of autism".
The scientists identified 473 autistic children born between 1979 and 1998. Their bowel problems and onset of developmental regression were documented from case records.
The proportion of children with regression or bowel symptoms did not change during the period, which included the introduction of MMR vaccination to Britain in October 1988.
These results suggest that neither regression nor bowel problems in these children was associated with MMR vaccination, the researchers concluded.
The findings provide further reassurance for parents and health professionals regarding the safety of the vaccine, they said.
Meanwhile, Mr Tony Blair has repeated his personal backing for MMR as it emerged that demand for the single measles vaccine has rocketed nine-fold in a year.
He stressed: "It is the responsibility of all of us, as parents, to ensure our children's health."
In remarks posted on the No 10 website, he insisted: "Against measles, mumps and rubella, the combined MMR vaccine is the best way of doing that."
PA