John Lennon and The Beatles (with Billy Preston) performed this unfinished song twice on January 28, 1969 during rehearsals for the aborted "Get Back" film/album project. Both of these performances have been bootlegged. The Beatles recorded rehearsal run-throughs of 'I Want You (She's So Heavy)' on January 29, 1969 while taping the "Get Back" sessions, however, none of these recordings have become available.

Thirty-five takes of this song were recorded on February 22 - the basic track and John's guide vocal. Paul McCartney sang lead on one of these takes which has been bootlegged. At this point, the song was known simply as 'I Want You'. Takes 9, 20 and 32 were edited together on February 23 to form the master take.

On April 18 John and George Harrison overdubbed guitars for the song's finale onto the February 23 master. A tape reduction (called take 1) of this master was prepared and more guitars were added. At the end of this day, a rough stereo mix was created. Hammond organ and congas were added to take 1 on April 20.

On August 8 John added Moog synthesizer sounds and noises to the original February 23 master tape, and Ringo Starr added drums. John, Paul and George recorded their harmony vocals on the line "She's so heavy" on August 11. These overdubs were added to both the February 23 master and the April 18 reduction mix-down. Eight stereo mixes of the April 18 mix-down (1 - 8) and two mixes of the February 23 master (9 - 10) were prepared August 20, 1969. Mixes 8 and 10 were edited together and the completed tape cut from 8'04" to 7'44" creating the sudden ending. This track was released on the "Abbey Road" album on September 26, 1969. It has been reported that a mono version of the "Abbey Road" album was released in England in September of 1970 on pre-recorded, open-reel tapes. No record of a mono mix of the tracks of the album exists. This may be a simulated mono release.

During an interview with Akiva Noff of Israeli Radio in the spring of 1969, John sang a bit of this song. This performance has been bootlegged and can be found on "Dig It" and "Good Night Vienna."

This song was recorded by Alvin Lee and released on his album "I Hear You Knockin'" in the UK in January 1994 and in the US ion March 22, 1994. George Harrison provided guitar for this recording.