They have released an e-fit image of the woman following the incident in Menston.
At about 6pm on Saturday a woman was at home in Main Street when she became aware of someone else in her house.
She went to investigate and found the stranger in the side porch.
The intruder claimed she was looking for a resident, whose name was not known to the victim, and then left on foot. Nothing was taken.
The intruder was white, in her 50s, about 5ft tall with long, straight brown hair which went about half way down her back.
Anyone who recognises her should contact Bradford CID on 101 or Crimestoppers on 0800 555111.