The National Housing Federation said East Hampshire will see the population of over-65s rise by more than a third to 27,300 by 2020.
It comes as number-crunchers have worked out the potential increase in pensioners given the existing population and desirability of the area.
The Federation has warned the surge will put a strain on housing and more affordable homes will have to be built over the coming years.
More 'pensioner friendly homes' must also be built, the Federation warned.
Warren Finney, regional manager for the Federation, said: 'These projections suggest a huge rise in the number of older people living in our south east villages and market towns, many of whom will live alone.
'That means we're going to be increasingly reliant on key services in these areas, as well as crucial housing and support services tailored specifically for older people.'
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