Only one in five people who experience symptoms of a transient ischaemic attack (TIA) call 999, the Stroke Association said.
More than one-third who have suffered a TIA thought it was just a "funny turn" and 47% did not believe it could be a medical emergency, the charity found.
In a new report, the charity said that if all TIAs were treated in time around 10,000 strokes could be prevented every year in the UK and more than 3000 lives could be saved.
Each year about 46,000 people in the UK suffer from a mini-stroke for the first time. One in 20 people will have a major stroke within two days of a mini-stroke and this figure rises to one in 12 within a week of a TIA.
The charity's poll of 670 stroke survivors across the UK also found one-quarter of people who had sought medical help said their healthcare worker did not recognise they had suffered a TIA, and 23% were given no information or advice on what lifestyle changes they could make to prevent a stroke.
TV presenter and stroke survivor Andrew Marr said: "I had two mini-strokes before going on to have a major stroke. I was one of the thousands of people who dismissed the warning signs - simple ignorance.
"Although I went on to have a stroke, my recovery has been jogging along well. Not everyone is that fortunate."
The Stroke Association said there needs to be better public awareness about mini-strokes. It said it is essential that health and social care workers can recognise the symptoms so patients can be referred quickly to a specialist. They should also be able to provide better information, support and advice so patients can make lifestyle changes.
Jon Barrick, chief executive of the Stroke Association, said: "The greatest risk of having a major stroke is within the first few days of a mini-stroke. When symptoms start call 999 and say you may be having a stroke. Urgently investigating and treating people who have a TIA or minor stroke could cut the risk of having another by 80%."