A man of 91 was robbed of £500 by two men who kicked open his front door.
The victim was ordered to sit in a chair while one man stood over him and his accomplice searched his home.
The men eventually fled after finding the pensioner had his life savings in his trouser pocket.
An ambulance was sent to the victim's home in Chichester as a precaution because he was so shocked.
The man is now being comforted by relatives and has helped detectives put together a description of the pair, who burst into his home on Tuesday night.
Detective Constable Neil Gilyead, in charge of the investigation, said: "This was a serious crime committed against a weak and vulnerable man in his own home.
"We are appealing for any witnesses or anyone with information to call in."
Both men are described as 6ft, with short brown hair and wearing dark clothes.
Mr Gilyead said: "The victim was very shocked by his ordeal."
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