Swinging Axe
- Label run by artist Randy Greif releases electronic, concrete and computer music.
- http://www.swingingaxe.com/

Shinkoyo
- Oberlin, Ohio label releases unusual avant electronic music from artists such as Skeletons, Peter B., and Severiano Martinez.
- http://www.shinkoyo.com

Supple Records
- New York based label specializes in ambient, experimental and space rock releases.
- http://www.supplerecords.org

Sounds Are Active
- Focuses on contemporary experimental hip-hop, free jazz and electronica. Artists include Bizzart, Create(!), and Xn.
- http://www.soundsareactive.com

Sijis Records
- London based label specializes in music with limited appeal and offers all their releases at low prices.
- http://www.sijis.com

Spectral House
- Austin, TX, based label founded by Brent Fariss and Bill Thompson publishes contemporary experimental music for internet mail order distribution.
- http://www.spectralhouse.com

SmallVoices
- Italian label dedicated to underground experimental music has released recordings of renowned Italian artists, largely on vinyl format.
- http://www.smallvoices.it/

Somnimage
- Experimental music label based in Illinois releases titles covering a diverse range of styles.
- http://www.somnimage.com/

Segerhuva
- Swedish label focuses on the most extreme end of the Scandinavian power electronics scene.
- http://www.segerhuva.se/

Shitkatapult
- A company based in Germany and Canada, focused on minimalist styles. Artists, dates, releases, profile, and contact.
- http://www.shitkatapult.com/

Shimamoto Sound
- A label that houses its own specially designed recording studio. Specializes in experimenting with traditional music styles to create innovative new sounds. Based in Massachusetts, USA.
- http://www.shimamotosound.com/

Silvergirl Records
- Releases Holiday Flyer, Gapeseed, and Track Star. Specializes in Indie-Rock and Experimental music. Includes artist profiles and reviews.
- http://www.silvergirl.com/

Sargasso
- UK based label and shop site for the Sargasso label artists.
- http://www.sargasso.com/

Summersteps Records
- With releases by artists such as Psychatrone Rhonedakk, Youth Aflame (The Choppers), Amasa, and Giraffe Hair. Also currently featuring "A Tribute to Jandek", with songs by Low, Amy Denio, Thurston Moore's Dapper, Gary Young, Monster Island, Rets
- http://www.summerstepsrecords.com/

Sub Rosa
- One of the first ambient and industrial music labels. They have re-released some of the defunct Rough Trade catalog. Located in Belgium.
- http://www.subrosa.net/index_fr.htm

Sloppy Abortion Records
- A noise and experimental label based in Jacksonville, Florida. Artists include Whimsical Fetus, The Smocks, Fuzzy Bunnies, and Mafia Dumptruck.
- http://www.liquidmethods.com/creative_web_design.html

simballrec
- Experimental music label releasing music by projects including Languis, Fer Chloca, Soulo, and Transistor Cricket.
- http://www.simballrec.com/

Skam Records UK
- Home to Gescom, Boards of Canada, and Bola. With RealAudio clips and downloads.
- http://www.skam.co.uk/

Sachimay Records
- An experimental/improvised label promoting artists such as Matt Weston, Tatsuya Nakatani, and Khristian Weeks.
- http://www.sachimayrecords.com/

Staalplaat
- An organization that includes a record label, print publisher, radio show, shop, mail-order and distribution for ambient dance, dark experimental, plunderphonic, sound poetry and electronic avant-garde music.
- http://www.staalplaat.com/

Squealer Music
- Record label with an international roster of refuseniks and experimentalists including High Rise, Spatula, William Hooker, Tono-Bungay, the Last Days of May, Charles Curtis, the Gold Sparkle Band, the Tower Recordings and others. Focused on improv, out-ro
- http://www.squealermusic.com/

Slum Communications and Darth Fuck Records
- Non-profit labels conspiring to revise and expand the underground electronic music movement.
- http://www.slum.org/

Selektion
- An ars organization and record label that is home to RLW, Achim Wollscheid, Charly Steiger and others.
- http://www.selektion.com/

Spectre Records
- Industrial, dark, doom, noise, and experimental record label. Small, but nice list of artists.
- http://www.spectre.be/

Soleilmoon Recordings
- Excellent site for dozens of ambient, experimental, and noise artists. Also an excellent store, for 30 underground labels.
- http://www.soleilmoon.com/

Sinusoidal Records
- An independent label based in Vancouver, Canada. With project sound samples, profiles, and links.
- http://www.sinusoidal.com/