The number of children being immunised with the three-in-one MMR vaccine is still too low, official figures disclosed today.
The target level is 95% but latest quarterly figures show that for two year-olds, the proportion has fallen from 92.8% to 92.3%.
Over the full year, however, the figures showed an increase - to 92.4% compared to 90.6% the previous year.
There were also signs that Scotland is close to achieving a World Health Organisation target of 95% uptake of the first dose of the measles, mumps and rubella vaccine by the age of five.
For the year as a whole the Scotland-wide figure was 94.1% - and in the final quarter it was 94.4%.
The vaccine was introduced in 1988 but uptake levels began to fall away after 1998 after a controversial study suggested it was linked to autism.
The alleged link was fiercely disputed by many health experts and uptake levels later began to pick up.
A Scottish government spokeswoman said: "We will work with health professionals to give parents the factual information they need to make an informed decision in favour of MMR.
"MMR uptake for the year to the end of March still shows an upward trend towards our target of 95%.
"We will continue to work closely with the NHS to meet this target."
But Tory health spokeswoman Mary Scanlon called the figures "worrying" and said that every parents should be offered the single vaccine alternative.
"It is not right that only the better off can afford to choose the treatment available to their children and I hope the new Executive will back our calls to end this practice," she said.
Ms Scanlon said: "Scottish Conservatives have always believed that MMR is the most effective way to tackle measles, mumps and rubella.
"However, given the number of parents refusing to have their children vaccinated with MMR, and the worrying number choosing not to vaccinate their children at all, alternative action must be taken."
The Liberal Democrats' Jamie Stone said: "Although we are close to achieving the World Health Organisation target of 95% uptake of the vaccine by the age of five, there are clearly still parents worried about possible negative health consequences of choosing the combined vaccine.
"I urge the Executive to launch a public awareness campaign addressing concerns about the alleged link between autism and the combined vaccine."