[1] Following the tour in support of their previous album, Trilogy (1972), the group acquired rehearsal facilities to work on new material, which would blend classical and rock themes.

Around January 1973 Keith Emerson, Greg Lake, Carl Palmer, and their manager Stewart Young decided to form their own record company.

Together, they bought an abandoned ABC cinema in Fulham, West London and converted it into a rehearsal room and company headquarters, which would later be named Manticore Records.

The most recognisable section of "Karn Evil 9" is the second part of the first movement, containing the famous line "Welcome back, my friends, to the show that never ends...", which was eventually taken as the title of the group's second live album.

[16] The next track intended for inclusion in the album was an adaptation of Hubert Parry's hymn "Jerusalem", with the lyrics from "And did those feet in ancient time", a short poem from the preface to William Blake's epic Milton.

Finally, the last piece, which would make the album, was the honky-tonk piano-based song "Benny the Bouncer" composed by Emerson, with Lake and Sinfield writing the words.

After the album was almost completely recorded, three additional tracks, which would be put on the shelf for a while, were written: the instrumental "When the Apple Blossoms Bloom in the Windmills of Your Mind I'll Be Your Valentine", credited to the entire group, "Tiger in a Spotlight" and the title song, both composed by Emerson, with Lake and Sinfield providing lyrics.

Following a period of further writing, the work on the upcoming album continued in August at Advision Studios in Fitzrovia, London, with engineer Geoff Young.

Although an arrangement of Ginastera's toccata had been performed by the group on their European tour from March to April 1973, the composition had received additional instrumentation before its final version was recorded.

In addition to its considerable evolution of synthesizer technology, Brain Salad Surgery also contained a higher proportion of songs featuring acoustic and electric guitars than their earlier work.

Since cover art for the impending album was required, Manticore manager Peter Zumsteg introduced Emerson to a popular artist, Hans Ruedi Giger, who was living in Zurich.

[22] Coincidentally, under the impact of the music, including Emerson, Lake & Palmer, Giger had just created a human skull-based triptych entitled Work 216: Landscape XIX.

It contains the artist's distinctive monochromatic biomechanical artwork, integrating an industrial mechanism with a human skull and the new 'ELP' logotype, which was also designed by Giger and has been standard for Emerson, Lake & Palmer ever since.

The front cover of the novelty triptych sleeve was split in half down the centre, except for the circular screen, which was attached to the right flap, and was opened up like a gate.

Prior to the album becoming available, British newspaper New Musical Express released an issue with an attached free promotional flexi disc[nb 5] on 10 November 1973.

However, it was later used as the B-side to the UK number two hit single "Fanfare for the Common Man" and ended up on the compilation of studio outtakes Works Volume 2 (1977).

[31] Instead of that song, the group's interpretation of "Jerusalem" was chosen for the single, which would be backed with another studio out-take, "When the Apple Blossoms Bloom in the Windmills of Your Mind I'll Be Your Valentine".

In the United States, Brain Salad Surgery was released in December 1973 by Manticore on vinyl record,[nb 8] cassette, and 8-track cartridge, and distributed by Atlantic.

In 2000, Rhino Entertainment Company released a DVD-Audio containing a 5.1 surround sound mix[nb 10], done by John Kellogg and Paul Klingberg.

In 2008, a remastered and expanded three-disc 35th-anniversary deluxe edition[nb 11] was released by Sanctuary Records, a subsidiary label of Universal Music Group at that time.

The original and new stereo versions in high resolution along with a brand new 5.1 surround sound mix by Jakko Jakszyk were featured on Disc 4 (DVD-Audio).

To mark the 50th anniversary a picture disc depicting the original Giger album artwork was released in the UK for Record Store Day on 22 April 2023.

Gordon Fletcher of Rolling Stone considered that although Emerson, Lake & Palmer managed to vanquish "insufficient intensity and lack of worthy material" of their previous records in live performances, these flaws overwhelmed all the group's positives in the studio, resulting in things like Brain Salad Surgery, which was deemed as a "sadly uneven album from a group with technical gifts equal to that of any British trio".

[37] Writing for The Village Voice, Robert Christgau, who had never been favourable towards Emerson, Lake & Palmer, submitted a review, which consisted entirely of rhetorical questions, and assigned the album a very low "C−" rating.

[39] In The Pittsburgh Press, critic Pete Bishop praised "the unmatched keyboard virtuosity of Keith Emerson," and called the album "a feast of sounds and imagination.

"[40] Before its release in the United States in December 1973, Brain Salad Surgery was reviewed by Billboard and described as "a complex, exciting sonic experience which touches on several bases—heavy rock, flowing jazz and some zesty pop material".

AllMusic contributor Bruce Eder cited the record as "Emerson, Lake & Palmer's most successful and well-realized album, and their most ambitious as a group, as well as their loudest".

[4] Paul Stump, in his 1997 History of Progressive Rock, characterized the album as frustratingly uneven, but highlighted the "demonic" version of "Toccata" and the group instrumental workout in the third part of "Karn Evil 9" as among the band's finest moments.

[42] While reviewing the box set A Time and a Place for the online All About Jazz magazine, John Kelman mentioned Brain Salad Surgery as a "crowning masterpiece" and the group's "undeniable high water mark".

The group carried almost 40 tons of equipment, which took five hours to unpack and set up, including a 30-channel board discrete quadraphonic public address sound system provided by International Entertainers Service, and a state-of-the-art lighting system, designed by Judy Rasmussen, which consisted of large ladders at each corner of the stage and two arches installed above the performance area.