Her son, Donto James, said Friday that his mother has been hospitalized for about a week with sepsis caused by a urinary tract infection.
She entered a treatment program to shake a dependency on painkillers and was transferred to the hospital when her condition worsened.
Etta James, who sang everything from blues to jazz, is best known for the hit "At Last."
Beyonce portrayed her and sang the song in the film "Cadillac Records" and at an inaugural ball for President Barack Obama.
