Scientists in Aberdeen say gardeners and farmers should wear protective clothing when using pesticides.
Parkinson's is a chronic irreversible brain condition
The researchers believe they have found a link between exposure to chemicals and an increased risk of Parkinson's.
Parkinson's Disease is a chronic irreversible brain condition - symptoms include tremors and muscle stiffness.
A study of 3,000 people, led by Aberdeen University, found that people with the disorder were more likely to have used pesticides regularly.
A third of those examined by the scientists were Parkinson's sufferers.
David Coggon, the chairman of the UK Government's pesticides advisory committee, said the study did not identify individual pesticides.
He said only one or two may be responsible.
"It's possible that just one or two are causing it, but slipped through the regulatory net," he said.
Around 120,000 people have Parkinson's in the UK - one in 500 of the population. Most are aged over 50.
The Geoparkinson study, funded by the European Commission, involved volunteers in Scotland, Italy, Sweden, Romania and Malta.
Researchers questioned 767 people with Parkinson's disease and a "control" group of 1,989 healthy individuals with similar backgrounds.
They found that low-exposure pesticide users, such as amateur gardeners, were 9% more likely than non-users to develop Parkinson's.
But high-exposure users, such as farmers, were 43% more vulnerable.
Principal investigator Anthony Seaton, from Aberdeen University said: "It considerably strengthens the case for pesticides being relevant to occupational risk of Parkinson's disease."
The Aberdeen researchers said pesticide risk is small when compared to other major factors in Parkinson's such as family history of the disease or being knocked unconscious.
Having a family history of the disease increased risk by 350%.
Being knocked unconscious once raised the risk by 32%, rising to 174% for those who have been knocked out several times.