Louvin was diagnosed with cancer last year and underwent surgery, but continued to schedule performances and even put out an album.
According to the Country Music Hall of Fame, the unique sound of the duet was highly influential in the history of the genre. The hall inducted them in 2001.
Among their hits were "I Don't Believe You've Met My Baby," which was No. 1 in 1965; "When I Stop Dreaming"; "Hoping That You're Hoping"; and "You're Running Wild."