'''EMX '''or '''EmX '''may refer to:
- emx+gcc, a DOS extender and DOS and OS/2 programming environment
- Emerald Express (EmX), a bus rapid transit system in Lane County, Oregon
- EuroManx, a defunct airline which held ICAO airline designator EMX
- El Maitén Airport, an airport in Argentina which has IATA airport code EMX
- Electribe EMX, music production station by Korg
EMX (Eberhard Mattes eXtender; also known as emx+gcc) is a programming environment for DOS and OS/2. It allows creating and executing of 32-bit mode applications, presenting a POSIX API and, on OS/2, access to the OS/2 APIs.