Binary system may refer to:
- Binary number system, the base-2 internal "machine language" of computers
- Binary opposition, a bipolar distinction in philosophy, structuralism and critical theory
- Binary system (astronomy), a system of two celestial bodies on a mutual orbit
- Binary asteroid
- Binary star
- Contact binary
- Contact binary (asteroid)
- Double planet
- In chemistry, a system involving two steps, processes or substances
- Mixture
- Azeotrope
- Binary System, a music duo featuring rock musician Roger Miller
ca:Sistema binari
pt:Binário