“This Old Heart of Mine (Is Weak for You)” is an Isley Brothers song from 1966 that was a hit for them during their brief tenure on Motown’s Tamla label. Featuring Ronald Isley on lead vocal, “This Old Heart of Mine” peaked at number twelve on the Billboard Hot 100, and at number six on the Billboard R&B Singles chart.
In 1975, Rod Stewart released a remake of this song that met with some success.
It became an even bigger international hit with a later 1989 version by Rod Stewart and Ronald Isley. Almost twenty-four years after the original recording, Ronald Isley and Rod Stewart released a Top 10 duet version of the song in 1989 that reached number ten on the US Billboard Hot 100 chart and spent five weeks at #1 on the US adult contemporary chart.