The stylistically modernist art-music chosen by Kubrick is similar to the repertoire he first explored in 2001: A Space Odyssey. Although the repertoire was selected by Kubrick, the process of matching passages of music to motion picture was left almost entirely at the discretion of music editor Gordon Stainforth, whose work on this film is known for the attention to fine details and remarkably precise synchronization without excessive splicing.
The soundtrack album on LP was withdrawn due to problems with licensing of the music. It remains only available on vinyl (there has never been a CD release) and is difficult to find. The LP soundtrack omits some pieces heard in the film, and also includes complete versions of pieces of which only fragments are heard in the film.
The non-original music on the soundtrack is as follows:
- "Lontano" by György Ligeti, Ernest Bour conducting the Southwest German Radio Symphony Orchestra (Wergo Records)
- "Music for Strings, Percussion and Celesta" by Béla Bartók, Herbert von Karajan conducting the Berlin Philharmonic Orchestra (Deutsche Grammophon)
- "Utrenja" – excerpts from the "Ewangelia" and "Kanon Paschy" movements by Krzysztof Penderecki, Andrzej Markowski conducting the Warsaw National Philharmonic Orchestra (Polskie Nagrania Records)
- "The Awakening of Jacob", "De Natura Sonoris No. 1" (the latter not on the soundtrack album, Cracow Philharmonic Orchestra conducted by Henryk Czyż) and "De Natura Sonoris No. 2" by Krzysztof Penderecki (Warsaw National Philharmonic Orchestra, conducted by Andrzej Markowski, Polskie Nagrania Records)
- "Home", performed by Henry Hall and the Gleneagles Hotel Band (Columbia Records)
- "It's All Forgotten Now" by Al Bowlly, performed by Ray Noble and His Orchestra (not on the soundtrack album)
- "Masquerade", performed by Jack Hylton and His Orchestra (not on soundtrack)
- "Kanon (for string orchestra)" by Krzysztof Penderecki (not on soundtrack)
- "Polymorphia (for string orchestra)" by Krzysztof Penderecki, Cracow Philharmonic Orchestra conducted by Henryk Czyż (not on soundtrack)
- "Midnight, the Stars and You" by Al Bowlly, performed by Ray Noble and His Orchestra (not on soundtrack)
Upon their arrival at Elstree Studios, Wendy Carlos and Rachel Elkind were shown the first version of the film by Kubrick: "The film was a little on the long side. There were great gobs of scenes that never made it to the film. There was a whole strange and mystical scene in which Jack Nicholson discovers objects that have been arranged in his working space in the ballroom with arrows and things. He walks down and thinks he hears a voice and a ghost throws a ball back to him. None of that made it to the final film. We scored a lot of those. We didn't know what was going to be used for sure". Carlos has said that she was so disillusioned by Kubrick's actions that she vowed never to work with him again. Her own music was released in its near entirety in 2005 as part of her Rediscovering Lost Scores compilation.