MTT can refer to:
- Dimethyl thiazolyl diphenyl tetrazolium salt, a type of tetrazole; see MTT assay
- IEEE Microwave Theory and Techniques Society, a society within IEEE focused on the theory and application of high frequency electronics.
- Magnetic Tow Technology, a technology developed by BMW
- Maria Theresa thaler, an originally Austrian coin used in many areas of the Near East and Africa.
- Marine Turbine Technologies
- Mario Teaches Typing
- Maritime Telephone and Telegraph Company, later known as MTT or MT&T
- Meaning-Text Theory, a theory in linguistics
- Metropolitan Transport Trust, the public body responsible for public transport in Western Australia from 1956 until 1987.
- Michael Tilson Thomas (nicknamed 'MTT'), an American conductor of the San Francisco Symphony, pianist and composer
- Military transition team, a group of embedded military advisors, sometimes abbreviated MiTT
- Minatitlán/Coatzacoalcos National Airport, IATA code MTT
- Modus Tolendo Tollens, the Latin name for an argument also known as denying the consequent
- MTT (Star Wars), a Multi-Troop Transport vehicle in the Star Wars Universe
- multi-table tournament, a type of poker tournament
- Municipal Tramways Trust, formerly the government authority charged with running the tram and bus network of Adelaide, South Australia