MMA may refer to:

• MacRobertson Miller Airlines , a Western Australian airline (1934-1980's).
• Manual metal arc welding
• Manufacturer's Mutual Association, former name for the Association of Licensed Automobile Manufacturers
• Methylmalonic acidemia, a genetic disorder
• MIDI Manufacturers Association , caretaker of the MIDI specification
• Mixed martial arts
• Montreal, Maine and Atlantic Railway
• Multimission Maritime Aircraft, a U.S. Navy program to replace the P-3 Orion with a Boeing 737-800-based platform.
• Muttahida Majlis-e-Amal, a coalition of "religous" political parties in Pakistan.