Scammers claiming to be BBC staff talked their way into an elderly woman's home claiming they had advice about the coronavirus pandemic.
Gwent Police said an 83-year-old woman let the two men into her home in Abertridwr, Caerphilly.
While nothing is thought to have been taken, the force is appealing for CCTV footage.
Insp Gavin Clifton said it was sad scammers were taking advantage of vulnerable people self-isolating.
Police were alerted at about 16:00 BST on Wednesday, but said it could have happened at any point between Saturday and Monday.
One of the men stayed downstairs with the woman, while the other went upstairs.
Insp Clifton urged anyone who might have seen the men talking to her, or who has any CCTV footage or dashcam footage from the street, to contact police.
"We want to remind people to cautious and vigilant at these times, particularly if you are approached by an individual, or individuals, claiming to represent an organisation offering details about the health crisis," he said.