"Biggest Mistake" is a song by The Rolling Stones from their 2005 album A Bigger Bang. It was released on 21 August 2006 as the third single from the album, and reached number 51 in the UK.
Credited to Mick Jagger and Keith Richards, the track is a pop song with a strongly acoustic guitar-based arrangement and lyrics that tell the story of an older man who falls in love but then walks out on his partner. It could be about the failed relationship between Jagger and model Jerry Hall. Beginning in late July, the song received extensive radio airplay, particularly on BBC Radio 2, where it remained on the A-Playlist for four weeks.