Brown agent Frank Copsidas told CNN Radio Brown was admitted to Emery Crawford Long Hospital with congestive heart failure and pneumonia. He fell ill during a dental appointment during the weekend.
Brown was credited with laying the foundation for funk and providing the roots for rap. He was variously known as the "Godfather of Soul," "The Hardest Working Man in Show Business," "Soul Brother No. 1" and "Mr. Dynamite."
Born in South Carolina during the Great Depression, Brown picked cotton as a child, shined shoes and danced for spare change. He met gospel leader Bobby Byrd while in reform school when he was 16 and turned to music when a leg injury derailed his semi-pro boxing and baseball careers.
Brown and Byrd formed the Flames after seeing Hank Ballard and Fats Domino in a blues review.
The biography on Brown's Web site, www.godfatherofsoul.com, says the singer transformed "gospel fervor" into the "explosive intensity of rhythm and blues, combined with precision choreography and dynamic showmanship" to define the direction of black music.
Funeral arrangements were pending.