The onetime model and Las Vegas showgirl was the fourth and final wife of "Ol' Blue Eyes", one of the 20th century's top film, TV, radio and concert entertainers.
Barbara and Frank Sinatra were married for nearly 22 years until his death in 1998.
John Thoresen, director of the Barbara Sinatra Children's Center, reported to CNN that Sinatra died of natural causes. She left Bosworth for California in her late teens after she was accepted to the Robert Edward School of Professional Modeling.
The pair married in 1976 and were together for 22 years until his death on May 14 1998. They divorced, and her son eventually adopted the name of her second husband, Zeppo Marx of the Marx Brothers. She married Marx in 1959, but their marriage collapsed in 1973 when she was caught having an affair with Sinatra.
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Instead, they enter Saturday's game against the New York Yankees at 48-50 and trailing New York and Tampa Bay by 3 1/2 games. Judge downplayed his homer, which he said he hadn't yet seen by the time he met with reporters after the game.
She remained active at the center until recently, pushing for creation of the video program just previous year and making sure the children had anything they needed, Thoresen said.
She is survived by her only child with first husband Robert and one granddaughter.
Barbara became involved in supporting and raising funds for a number of charitable projects years after she married Sinatra.
In a statement, her foundation wrote, "Through Barbara Sinatra's efforts, more than 20,000 children through age 18 have received beneficial therapy at [the center], making it possible for them to cope with traumas associated with abuse". The organization, founded in 1986, advocates for and provides counseling to victims of child abuse.