Leon Russell is said to be stable after suffering a heart attack last week.
The 74-year-old is currently undergoing tests, according to the Oklahoma Historical Society, and is scheduled for surgery in Nashville this week.
Russell’s representatives say they’re optimistic that the Grammy-winning artist will make a full recovery.
His 24-date US tour has been postponed, with his website stating the shows will be rescheduled at a later date.
Russell has released dozens of solo albums throughout his career, including his 2010 collaboration The Union with Elton John.
The film A Poem Is A Naked Person by Les Blank which documented Russell’s studio work between 1972-1974 was recently released on DVD and Blu-ray for the first time.
Leon Russell postponed 2016 tour dates
Jul 21: Key West Theater, FL
Jul 22: Boca Raton The Funky Biscuit, FL
Jul 23: Boca Raton The Funky Biscuit, FL
Jul 24: Clearwater Capitol Theatre, FL
Jul 25: Melbourne King Center Of The Performing Arts, FL
Jul 27: Pensacola Vinyl Music Hall, FL
Jul 28: Baton Rouge Varsity Theatre, LA
Aug 05: Kansas City Knucklehead Saloon, MO
Aug 07: Sturgis The Buffalo Chip, SD
Aug 09: Missoula Wilma Theatre, MT
Aug 13: Morristown Big Wu Family Reunion, MN
Aug 14: St Louis The Ready Room, MO
Sep 02: Milwaukee The Pabst Theater, WI
Sep 18: Houston House Of Blues Houston, TX