Scientists found that walking at least one to two hours a day was associated with reduced stroke risk.
But strenuous "power walks" were not required. Length of time spent walking had a bigger impact than the speed of walking.
Findings from the study of 3,435 healthy men aged 60 to 80 appear in the American Heart Association journal Stroke.
Participants were questioned about the distance they walked each week and their usual walking pace.
The research showed that men who walked for eight to 14 hours each week were a third less likely to suffer a stroke than those who spent no more than three hours walking.
For men walking more than 22 hours a week, the risk was two thirds lower.
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"If you took 1,000 men who usually walk 8-14 hours per week and followed them for 10 years, on average they would have 55 strokes, compared with 80 for the group who only walk zero to three hours per week," said lead researcher Dr Barbara Jefferis, from University College London. "The total time spent walking was more consistently protective against stroke than walking pace; overall it seemed that accumulating more time walking was most beneficial.
"Our findings suggest that regular walking each week could be an important part of stroke prevention strategies in older people."
Each year in the UK around 152,000 people suffer strokes, which can be fatal or disabling.
Dr Shannon Amoils, from the British Heart Foundation, which part-funded the study, said: "Whatever your age it's important to stay active every day. This research suggests a daily walk could help to reduce stroke risk and is further evidence that regular exercise - even a daily stroll in the park - can be an effective way to keep healthy."