The screen legend told her ninth husband Prince Frederic von Anhalt: ‘There is something missing’ as the horror dawned on her.
Nobody had been able to the 95-year-old for fear it would cause too much upset, the New York Post reported.
Heartbreaking: Zsa Zsa Gabor, pictured here with husband Prince Frederic von Anhalt in August last year, only realised her leg had been amputated 18 months after the event when she tried to sit up and saw it was missing
Miss Gabor was unable to make the discovery herself because one hand is paralyzed and the other is too short to reach.
She has been in declining health since a car crash in 2002 and an accident in 2010 when she fell out of bed whilst trying to answer the telephone.
In January last year she had her right leg amputated above the knee after doctors found an infection and antibiotics failed to cure it.
Miss Gabor is now confined to her bed at her Los Angeles mansion.
Mr von Anhalt admitted that along with not telling her about her leg, she ‘doesn’t know she gets food through the tube’.
Heyday: The actress enjoyed a long film career seen here in the 50s film Lovely to Look At
He said: ‘It will only upset her. She was so glamorous always, and she is so vain.’
He also confessed to not informing her of the death of her friend Phyllis Diller last month as ‘I don’t want to give bad news to my wife.’
Hungarian-born Miss Gabor became a sex symbol in the 1950s and was known for her pithy comments on her colourful love life.
She once said: ‘I am a marvellous housekeeper. Every time I leave a man, I keep his house’.
Mr von Anhalt was recently appointed her temporary conservator after a court battle with her daughter Constance Francesca Hilton.