The incident happened in the Drumgor Park area of Craigavon, Co Armagh.
Police say that at around 11.20 pm an unknown male entered the bedroom of an elderly woman claiming to be a police officer.
He then proceeded to search through drawers. He made off with a sum of money. It is believed that there may have been a second male in the house.
The elderly woman was not injured during this incident, however she was left very badly shaken.
Detectives would ask anyone who has any information about this incident to contact them at Lurgan on the non emergency number 101.
Or, if someone would prefer to provide information without giving their details, they can contact the independent charity Crimestoppers and speak to them anonymously on 0800 555 111.