The longtime DJ was known for his radio shows featuring music from Frank Sinatra, which aired across the country.
Mark launched "The Sounds of Sinatra" in Philadelphia more than 65 years ago.
He also developed "Friday with Frank" and "Sunday with Sinatra."
Radio station 1210 WPHT says Mark died Monday night.
A post on The Sounds of Sinatra Facebook page read:
"We lost our leader last night as Sid Mark has passed away. He loved his family and of course Mr. S., and his dedicated audience. The Legend Will Continue."
There was no immediate word on a cause of death.
The show posted audio of Sinatra speaking about his friend during a 1991 performance at the Spectrum.
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