The incident happened at around 8.15pm on Sunday, when a man was approached by four men who had been in a parked car close to the property on Madden Row, Crossmore.
They forced the man to open the back door of his house and ordered him to stay in a room.
They made off with a sum of cash.
The thieves were all wearing dark jackets and baseball caps and spoke with southern accents. They were travelling in a dark saloon car.
Anyone who has information on the incident is asked to contact the PSNI.