- Ubiquital I (1971), 10:002 flutes, 2 clarinets, saxophone quartet, 4 horns, prepared Hohner clavinet, 4 violins, 4 cellos and percussion
- Ubiquital II (1972), 18:00flute (also piccolo), clarinets, oboe, contrabassoon, saxophone quartet, horn, trumpet, trombones, tuba, 4 percussions and string quintet
- Ubiquital III (1972), 15:00flute, oboe, clarinets, contrabassoon, saxophone quartet, horn, trumpet, trombones, tuba and piano
- Udvarim Achadim (2010), 17:00saxophone quartet
- L’ultima sera (1980)female voices and 5 instruments
- UN 9 (1987)2 trumpets, 2 percussions and mime
- Un bal masqué (1991), 9:30
- Un bouquet de brume (2012-13), 5:00bass flute and piano
- Un bouquet de brume (1998), 8:00Arr. Ana Sokolović, 2011bass flute and pianoOriginal work: Un bouquet de brume
- Un cri qui durerait la mer (1985)contralto and piano
- Un fleuve, une île, une ville (1991-92), 12:00orchestra
- Un lieu verdoyant — Hommage à Gérard Grisey (1999), 6:00soprano and saxophone
- Un prélude hétéroclite (2010)
- Un train pour l’enfer (1993), 15:00ensemble (piccolo, oboe, clarinet, bass clarinet, bassoon, horn, trumpet, trombone, two violins, viola, cello, double bass, piano, percussion) and 6 percussions
- The Unanswered Question (1908)2 flutes, oboe, clarinet, trumpet, 2 violins, viola and cello
- Une autre création du monde (1982), 21:48
- Une Fleur du Mal (mélodrames d’outre-tombe) (1992), 19:00soprano, clarinet, percussion and cello
- Une petite musique de nuit d’été (1994), 6:004 guitars or more
- Une petite note dans le système (2015), 10:00
- … une pierre qui roule! [… a rolling stone!] (1993), 10:00flute, oboe, clarinet, violin and cello
- Une prière pour Zipangu (2011), 15:003 types of solo flutes, rin gong and scenic installation
- Une saison en enfer (1980), 44:27voice, piano, percussion and 8-channel fixed medium
- Mauvais sang, 10:34
- Soli piano / percussions, 5:43
- La nuit de l’enfer, 4:14
- Cadence de piano solo, 3:48
- «Ô Saisons, Ô châteux…», 2:55
- Unguis incarnatus est (1972)harmonium and piano
- L’Union à la une (2003), 16:00mezzo-soprano, chamber orchestra and digital sounds
- Unrevealed Cube 4x4 (2010)
- [untitled] (2012)
- Upload (2008)
- Ur (1998-2001)oboe d’amore
- Urantia, Nr 99 (2007), 20:00soprano and fixed medium
- Uraufführung (1977)string quartet, 3 flutes, bass flute, bass clarinet, bassoon, horn, guitar and percussion
