"Scar Tissue" is the first single from American rock band Red Hot Chili Peppers' seventh studio album, Californication (1999). Released on May 25, 1999, the song spent a then-record 16 consecutive weeks atop the US Billboard Hot Modern Rock Tracks chart as well as 10 weeks atop the Billboard Mainstream Rock Tracks chart, and it reached number nine on the Billboard Hot 100.
It was also successful in Iceland, New Zealand, and Canada, reaching numbers one, three, and four, respectively. In the United Kingdom, it charted at number 15 on the UK Singles Chart.
"Scar Tissue" is considered to be representative of the new, more melodic rock sound the band experimented with on Californication (in contrast to the psychedelic One Hot Minute, and dry funk of Blood Sugar Sex Magik). The song is notable for its mellow intro guitar riff and for its slide guitar solos throughout. Guitar World placed the guitar solo 63rd in its list of the "100 Greatest Guitar Solos".
"Scar Tissue" won a Grammy Award for Best Rock Song in 2000.
In 2004, Anthony Kiedis published an autobiography titled after the song. Co-written by Larry Sloman, its principal theme was sex, drugs and rock-'n-roll. In the book he talks about the consequences of drugs (especially heroin) and how this can destroy a person's life.