AAD is a three-letter acronym that may refer to:

• Advanced Air defense, India's defense program to develop a multi-layer Ballistic missile defense shield.
• AAD Education, Health and Sports (formerly, Athletes Against Drugs)
• Administrative Accompanying Document, an EU document to control duties within the Union and member states.
• American Academy of Dermatology
• Anamoly Appreciation Day

• Antibiotic-associated diarrhea
• 7-Amino-actinomycin D (7-AAD), a fluorescent stain for DNA
• ASCII Adjust before Division, an Intel 80x86 processor instruction
• Associação de Activismo para a Democracia, a political party in Macau
• Australian Antarctic Division, which manages Australia's four Antarctic/sub-Antarctic stations, as well as Heard Island
• Automatic activation device, a "fail-safe" device often used in a parachute pack to automatically deploy the reserve if a predetermined altitude is passed at a high rate of speed
• Analog, analog, digital, a three-letter code for a CD that was recorded analog, mixed analog, and transferred digitally
• IATA airport code for Ad-Dabbah Airport in Ad-Dabbah, Sudan
• ICAO airline designator for Aero Aviation Centre Ltd. in Canada
• Armee-Aufklärungsdetachement 10 Switzerland's new SAS-type Special Forces unit, which is an all-volunteer professional unit with a rigorous selection process
• average absolute deviation in statistics, a way to report error against reference data
• Ad Altare Dei, a Religious emblems programs (Boy Scouts of America) given to Roman Catholic members of the Boy Scouts of America for completing a series of requirements`