AMA, a three-letter abbreviation, may refer to:

• Academy of Model Aeronautics
• Actual mechanical advantage
• Advanced Mobile Applications, a company spacialised in manufacturing non-game, entertainment applications for mobile terminals
• Against medical advice, a patient leaving a medical facility early and against the advice of medical staff
• Agence Mondiale Antidopage, the World Anti-Doping Agency
• Alberta Motor Association
• American Management Association
• American Marketing Association
• American Medical Association
• American Motorcyclist Association
• American Music Awards
• Anime Mid-Atlantic
• Argentinean Manitoban Association
• Associación Médica Argentina
• Australian Medical Association
• Autoridad Metropolitana de Autobuses ("Metropolitan Transit Authority"), a public corporation based in Puerto Rico that manages the mass transit bus system on the island
• Automatic Message Accounting, an electromechanical billing system
• AMA Computer University
• AMA, the IATA airport code for Rick Husband Amarillo International Airport
• Association of Members Advocates, a Wikipedia organization