No official cause of death was announced by the Chicago Tribune, where Siskel served as film critic for three decades. However, Siskel had never seemed to fully recover from surgery last May to remove an unspecified "growth" from his brain.
Roger Ebert, Siskel's longtime sparring partner on their eponymous TV show, said, "Gene was a lifelong friend, and our professional competition only strengthened that bond."
"He showed great bravery in the months after his surgery, continuing to work as long as he could," Ebert continued.
"As a critic, he was passionate and exacting. As a husband and a father, his love knew no bounds. My wife, Chaz, and I extend our deepest sympathy to his wife, Marlene, his children and his family."
Following his surgery, Siskel almost immediately returned to work--the syndicated show with Ebert (he phoned in reviews from his hospital bed), the columns in TV Guide and the Tribune, the CBS This Morning appearances.
But earlier this month, the producer of Siskel & Ebert said the so-called "skinny one" would heed the advice of doctors and take a six-month sabbatical from all work to recuperate at his home. Just this week, Washington Post critic Tom Shales was tapped as a temporary TV replacement.
Siskel and Ebert had been an on-air team since 1975, when a Windy City PBS producer had the bright idea to pit the film critic for the Chicago Tribune (Siskel) against the film critic for the Chicago Sun-Times (Ebert). No immediate word on the future of the influential show.
Siskel is survived by his wife, Marlene, and three children.