Isabel was not a patch on her husband, possessing slight political acumen and negligible popular appeal.
Now 64, she came into Peron's life in the mid-1950s wearing a skimpy ostrich-feather dress in the Happyland nightclub in Panama, when the general was in exile after a military coup overthrew his first regime in 1955. Eva Duarte - Evita - his glamorous former wife, had died two years before. Isabel was a pale mockery of her predecessor, although after she became President, she bleached her hair in a vain attempt to resemble Evita.
Mrs Peron spoke poorly. She would harangue the public from the Casa Rosada, as Peron had done, raising and lowering both arms as he used to do, shrieking in a shrill tone, that no one who heard it can forget.
Not only the sound but the content of her words sent shivers down spines. Manipulated by her sinister Labour Minister, Jose Lopez Rega, known as El Brujo (the wizard) for his interest in the occult, she fired the opening shots in Argentina's "dirty war'', signing a decree in 1975 that gave the armed forces a free hand to liquidate "left-wing subversives" and allowed the infamous Triple-A death-squads to roar around the capital with rifles, taking people off the streets and into oblivion.
The military were clever enough to realise that with this unstable twosome in control, all they had to do was wait. When the tanks rolled after nearly two years of chaos, many people greeted them with relief.
Isabel was packed off to comfortable exile in Spain. But with the return of democracy in the early 1980s, she moved back into the political arena. In October 1988, she was invited back by the leader of the Radical Party, President Raul Alfonsin. Carlos Menem, the Peronist presidential candidate, was hostile.
"Mrs Peron knows nothing of politics," he sneered. She did not stay long.
Latterly, Mrs Peron has lived in Madrid, where she passes the time shopping, socialising and attending art openings.
Last month, she resurfaced in the Argentine debate over the fate of desaparecidos thrown from aircraft into the sea. "I prefer to keep silent," she said. "When those who lead the destinies of a country have anything to say, they should say so at the time, and if not, shut up."