The 84-year-old woman was robbed in her home by another woman who pretended to know her.
The thief visited the woman at her house in East Road, Irvine, North Ayrshire at around 2.45pm on Friday.
She chatted to the woman for an hour after being allowed into the property.
Once the woman left, the elderly householder noticed a four figure some of cash was missing.
Police have launched an appeal for witnesses following the incident.
The suspect is described as white, around 30-years-old, of slim build with brown hair in a pony tail.
She was wearing a blue jumper or a cardigan with a knee length skirt.
Detective Constable Alex Greig of Irvine Police Office said: "People who target elderly members of the public in their own homes are despicable, and it is totally unacceptable to leave elderly people feeling vulnerable in their own home.
"I would urge anyone in the local area who recognises the description of this woman, or who may have also been targeted by her to come forward to police."
Anyone with information should contact 101, the non emergency number for Police Scotland.
Alternatively Crimestoppers can be contacted on 0800 555 111, where anonymity can be maintained.