"Heart Full of Soul" is a 1965 single by the English rock band The Yardbirds. It was written by Graham Gouldman, who would later have a successful career as a member of 10cc. It charted in the United States at number nine and at number two in the United Kingdom. The song makes an early use of the fuzz box by guitarist Jeff Beck during the guitar solo. Originally, a sitar was going to be used, in keeping with the "Eastern-exotic" atmosphere of the song, but the sound was too thin, and eventually Beck produced a sitar-like effect on the electric guitar. An outtake exists, with the sitar part intact.
The B-side of the UK, US, German, Italian, and Irish releases was "Steeled Blues" written by Keith Relf and Jeff Beck.
In one way or another, all three of The Yardbirds' key guitarists were involved with "Heart Full of Soul". Although it is Beck that plays on the song, the US single was released with a picture sleeve erroneously showing the Eric Clapton line-up. A March 1968 appearance on the music show Upbeat featured the final line-up with Jimmy Pagemiming to the record.