A survey by the charity Age UK found that 29 per cent of respondents believe they were targeted by con artists at some point during the year, with 17 per cent of those actually falling victim.
Online deception was the most common fraud, the poll found, followed by bogus phone calls.
Age UK questioned 4,732 people across the UK as part of their research into scams. The results showed fraudsters targeted all age groups, and men were as likely to be conned as women.
But the charity warned that older people were more commonly victims of time share and holiday club frauds, with 17 per cent of those being hit aged between 70 and 79.
Researchers also found that victims were reluctant to admit they had been conned.
Only 8 per cent of those fooled by con artists went to the police. Almost three-quarters did not even tell a friend or family member.
Helena Herklots, services director at Age UK, said: "The evidence shows that scamming is rife. We are working to raise awareness of the issue and provide information and advice to help older people avoid being conned."
She added: "Remember, if it sounds too good to be true, then it probably is."