Her jealous husband even banned her from watching TV or seeing their two grown-up children, she said. He beat her and locked all doors and windows whenever he went out.
The woman's ordeal began the day they wed in 1958.
She emerged when she was admitted to hospital with heart trouble in Trento, Italy.
The couple was not identified.
He locked her inside the house when he went out, and would not even let her watch the television.
"Once the hospital informed us of the woman''s story we acted immediately and informed the local prosecutor," the Telegraph quoted a police spokesman, as saying.
"It appears that the woman was kept a virtual prisoner in her own home for 50 years. She was only allowed out when her husband was with her and if he went out on his own he would lock all the doors and windows.
"At 5pm when he came back he would lock the place down, She was not even allowed to see her children and they were not allowed to visit.
"The TV was also forbidden and there were also times when he would beat her.
"It''s a very sad story and the woman''s life has been made a misery by her husband - if it wasn''t for the fact she was admitted to hospital and bravely decided to speak out her ordeal would have continued," the rep added.
Trento prosecutor Fabio Biasi requested an order for the man to be removed from his house and taken to secure accommodation while the investigation continued.