"Bad Blood" is a popular song written by Neil Sedaka and Phil Cody. The song, with uncredited backing vocals by Elton John, reached number one on the Billboard Hot 100 in 1975, remaining in the top position for three weeks. It was certified Gold by the RIAA and was the most successful individual commercial release in Sedaka's career. "Bad Blood" was replaced at the number 1 spot by John's single "Island Girl".