"Thunder in My Heart" is a song by English-Australian singer Leo Sayer, from his fifth studio album, Thunder in My Heart (1977). The song was written by Sayer and Tom Snow, while produced by Richard Perry. It was released through Warner and Chrysalis Records in 1977, as the first single from the album. The disco song consists of a bassline and strings. "Thunder in My Heart" received generally positive reviews from music critics, who praised the production. It peaked at number 22 on the UK Singles Chart and at number 38 on the US Billboard Hot 100. A dance remix of the song by British disc jockey Meck titled "Thunder in My Heart Again" was released on 6 February 2006, and topped the UK Singles Chart.

Gerard Hugh "Leo" Sayer is an English-Australian singer and songwriter who has been active since the early 1970s. He has been an Australian citizen and resident since 2009.