The pensioner, from Stoney Road, Priestwood, Bracknell, went to answer the door at about 5.23pm on Monday of last week and was asked by the two men outside if they could borrow a pen and some paper.
When the victim asked them to wait, one man pushed his way in and threatened the woman, saying: "I'll kill you. Give me money for drugs."
The second man then ransacked the house before the pair made off with £160 in cash.
Police, who only released details this week, described the incident as "bizarre" and warned other elderly residents, especially those living alone, to be careful when answering the door to strangers.
PC John Oblein, crime reduction officer at Bracknell police, said: "This was a very disturbing and bizarre burglary, but thankfully it was an unusual kind of offence which does not happen every day.
"However, distraction burglaries in general are taken very seriously, and we would advise elderly residents to be extra careful and make sure they use their doorbar and chain when answering the door."
He could not confirm if the offenders in the latest incident were definitely drug addicts or if they had used the threat to terrify the victim more, but said the offence and the threats would be taken "very seriously".
The victim was only able to provide a description of one of the men.
He was in his 20s, of heavy, "towards fat", build. He was over 5ft 5in, with short mousy hair in no specific style. He was also clean shaven and well spoken, with a local accent.
The man was wearing a long-sleeved knitted blue top, close fitting around the neck, and light trousers, possibly brown.
He and his accomplice made off on foot from the house towards Binfield Road, but they are not believed to have had a car.
News of the burglary comes in the week the Government's Minister for Drug Policy, Bob Ainsworth, warned that crack cocaine use was "spreading out from London to other parts of the country" and that addiction was often so strong, users resorted to burglary, street robbery and shoplifting.
Anyone with information on the incident in Bracknell is urged to call PC Wayne Reece at Bracknell police on (01344) 823456 or Crimestoppers anonymously on 0800 555111.
l Older residents are being encouraged to take advantage of the Berkshire Bobby Scheme administered through Bracknell police.
It involves a qualified locksmith fitting extra security devices for free to provide extra home safety.
For more details, call PC John Oblein on (01344) 823483.