The song was the band's seventh number 1 single on the Billboard Hot 100, a run of US chart success achieved in just over a year.

It also provided the title for director Ron Howard's 2016 documentary film on the band's years as live performers, The Beatles: Eight Days a Week.

[5] "Eight Days a Week" was the first song that the Beatles took into the studio unfinished to work on the arrangement during the session, a practice that would become common for the band.

[6] "Eight Days a Week" was one of the first pop songs to open with a fade-in (only select examples exist prior such as Johnny Horton's "The Wild One").

[12] Describing the unusual effect provided by the fade-in, particularly at the start of an LP side, author Mark Hertsgaard writes that it gave listeners "the sensation of hearing the music before the song actually arrived; it was as if the sound arose out of the distance, like a flock of migrating birds that suddenly fills the sky.

In the end, it was released as a single in the United States on 15 February 1965 (as Capitol 5371),[13] becoming a number-one hit (their seventh in that country).

[14] Cash Box described it as "a hard-driving, rollicking pledge of romantic devotion with a contagious repeating rockin’ riff.

[19] It was the last of seven songs by the Beatles to top the Billboard Hot 100 over a one-year period, marking an all-time record for a single act.

The song was also the second of six Hot 100 chart toppers in a row (not counting the EP 4 by the Beatles) by one act, another record at the time.

[20] According to Ian MacDonald, except where noted: Although it was a huge American hit, the group did not think highly of the song (Lennon called it "lousy")[21] and they never performed it live or at any of their radio sessions for the BBC.