“I Feel Fine” is a song written by John Lennon (credited to Lennon–McCartney) and released in 1964 by the Beatles as the A-side of their eighth British single. The song has one of the first uses of guitar feedback in popular music.
Lennon wrote the guitar riff while in the studio recording “Eight Days a Week”. “I wrote ‘I Feel Fine’ around that riff going on in the background”, he recalled. “I told them I’d write a song specially for the riff. So they said, ‘Yes. You go away and do that’, knowing that we’d almost finished the album Beatles for Sale. Anyway, going into the studio one morning, I said to Ringo, ‘I’ve written this song but it’s lousy’. But we tried it, complete with riff, and it sounded like an A-side, so we decided to release it just like that.” Both John Lennon and George Harrison said that the riff was influenced by a riff in “Watch Your Step”, a 1961 release written and performed by Bobby Parker and covered by the Beatles in concerts during 1961 and 1962. Paul McCartney said the drums on “I Feel Fine” were inspired by Ray Charles’s 1959 single “What’d I Say”.
At the time of the song’s recording, the Beatles, having mastered the studio basics, had begun to explore new sources of inspiration in noises previously eliminated as mistakes (such as electronic goofs, twisted tapes, and talkback). “I Feel Fine” marks one of the earliest examples of the use of feedback as a recording effect in popular music. Artists such as the Kinks and the Who had already used feedback live, but Lennon remained proud of the fact that the Beatles were perhaps the first group to deliberately put it on vinyl.
“I Feel Fine” is written in 4/4 time with drummer Ringo Starr’s R&B-influenced beat (based on the “Latin” drumming in Ray Charles’s hit “What’d I Say”) featured through most of the song except for the bridge, which has a more conventional backbeat. After a brief note of heavy feedback (see below), the intro begins with a distinctive arpeggiated riff which starts in D major before quickly progressing to C major and then G major, at which point the vocals begin in G. The melody, unusually, uses a major third and a minor seventh, and has been classified as Mixolydian mode. Just before the coda, Lennon’s intro riff (or ostinato) is repeated with a bright sound by George Harrison on electric guitar (a Gretsch Tennessean). The song ends with a fadeout of the G major portion of the opening riff repeated several times.
“I Feel Fine” starts with a single, percussive feedback note produced by McCartney plucking the A string on his bass, and Lennon’s Guitar (which was leaning against McCartney’s bass amp) picking up feedback. This was the first use of feedback on a rock record. According to McCartney, “John had a semi-acoustic Gibson guitar. It had a pickup on it so it could be amplified…. We were just about to walk away to listen to a take when John leaned his guitar against the amp. I can still see him doing it…it went, ‘Nnnnnnwahhhhh!’ And we went, ‘What’s that? Voodoo!’ ‘No, it’s feedback.’ ‘Wow, it’s a great sound!’ George Martin was there so we said, ‘Can we have that on the record?’ ‘Well, I suppose we could, we could edit it on the front.’ It was a found object, an accident caused by leaning the guitar against the amp.” Although it sounded very much like an electric guitar, Lennon actually played the riff on an acoustic-electric guitar (a Gibson model J-160E), employing the guitar’s onboard pickup.
Later, Lennon was very proud of this sonic experimentation. In one of his last interviews, he said, “I defy anybody to find a record—unless it’s some old blues record in 1922—that uses feedback that way.” 
Two different music videos directed by Joe McGrath were filmed on 23 November 1965. Both feature various bits of gym equipment. In the first, George sang into a punch-ball while Ringo pedalled on an exercise bike. The second marked the only time a lunch break was filmed, where they all ate fish and chips, while trying to mime to the song. Brian was adamant that this video could not be used. From then on, the controversial “fish and chips” footage was kept in a 2″ videotape box labelled “I Feel Fried”. The first music video was included in the Beatles’ 2015 video compilation 1, and both videos were included in the three-disc versions of the compilation, titled 1+.
The single reached the top of the British charts on 12 December 1964, displacing the Rolling Stones’ “Little Red Rooster”, and remained there for five weeks. In Canada, the song also reached number one. 
“I Feel Fine” was also the first Beatles single to be released almost concurrently in the US and the UK. The song has sold 1.41 million copies in the UK.
The song topped the US Billboard Hot 100 charts for three weeks in late 1964/early 1965. Cash Box magazine ranked “I Feel Fine” as the 19th biggest U.S. hit of 1965. The B-side was the number-four hit “She’s a Woman”.
“I Feel Fine” was the sixth single by the Beatles to hit number one on the Billboard Hot 100 in a calendar year (1964); an all-time record. In order, these singles were “I Want to Hold Your Hand”, “She Loves You”, “Can’t Buy Me Love”, “Love Me Do”, “A Hard Day’s Night” and “I Feel Fine”. For songwriters Lennon and McCartney, it was the seventh number-one they wrote in the same calendar year (1964), another all-time record (see List of Billboard Hot 100 chart achievements and milestones).
The song was the first of six Hot 100 number one chart toppers in a row (not counting the EP “4 – by the Beatles”) by one act, also a record at the time. The subsequent singles were “Eight Days a Week”, “Ticket to Ride”, “Help!”, “Yesterday” and “We Can Work It Out”.
In the United States, the song was released on the Capitol album Beatles ’65. The mono version — also released as a single on Capitol — features an exclusive mix with added reverb and a shorter fade as created by Beatles producer George Martin. The stereo version of the LP presented a duophonic mix featuring a layer of reverb added by executive Dave Dexter, Jr..
In the United Kingdom, the song was released on the LP format on A Collection of Beatles Oldies. A true stereo version can be found on the Past Masters Volume 1 and 1 CDs.
There is also another stereo version (virtually identical to the standard stereo mix) wherein whispering can be heard at the beginning of the track. This “whispering version” appears on the non-US release of 1962–1966, as well as on occasional single re-releases.
An outtake in mono is included in the On Air – Live at the BBC Volume 2 compilation released in 2013.
John Lennon – double tracked lead vocal, lead/rhythm guitar
Paul McCartney – harmony vocal, bass
George Harrison – harmony vocal, lead/rhythm guitar
Ringo Starr – drums