AAU may stand for:

• Antillean Adventist University, a Christian university in Mayagüez, Puerto Rico.
• Amateur Athletic Union, a United States sports organization.
• Association of American Universities
• Association of African Universities
• Addis Ababa University
• Assam Agricultural University
• Asian Americans United is registered with the Commonwealth of Pennsylvania as a Charitable Organization.
• Acute anterior uveitis, an inflammatory joint disease