MDA is an abbreviation for

• Moldova (its ISO 3166-1 three-letter country code);
• two organizations in the U.S.:
  • the Muscular Dystrophy Association;
  • the Missile Defense Agency, an agency of the Department of Defense;
• various computing terms:
  • the OMG's model-driven architecture;
  • Monochrome Display Adapter, a computer display standard;
  • Mail Delivery Agent;
• 3,4-methylenedioxyamphetamine (MDA), a drug closely related to MDMA.
• the name of a television program produced by the Australian Broadcasting Corporation.
• Magen David Adom - the Red Cross of Israel