UD may refer to:
In education:
- University of Dallas, a Catholic university in Texas
- University of Dammam, a Saudi university in Dammam, Eastern region of Kingdom of Saudi Arabia
- University of Dayton, a university in Ohio
- University of Delaware, a university in Delaware
- University of Detroit Jesuit High School and Academy, a Catholic secondary school in Michigan
- University of Detroit Mercy, a Catholic university in Michigan
- University of Dublin, a university in the Republic of Ireland
- University of Dubuque, a Presbyterian university in Iowa
- University of Durham, a university in the United Kingdom
Businesses:
- UD Trucks, a Japanese truck manufacturer
- United Devices, a commercial distributed computing company that focuses on CPU scavenging and enterprise cluster management
- United Distillers, a whiskey holding company
- Upper Deck, a manufacturer of collectibles and trading cards
- Hex'Air (IATA airline designator)
In entertainment:
- Oud, a Middle Eastern musical instrument
- Urban Dead, a massively multi-player online role-playing game
- Undead, particularly in the Warcraft universe
Other uses:
- Ulster Defence Regiment Medal, a UK military medal
- Unanimous decision, usually referring to combat sport victories
- Universal Declaration of Human Rights, a declaration adopted by the United Nations General Assembly
- Urban Dictionary, an online reference for slang terminology
- Utenriksdepartementet, the Norwegian Ministry of Foreign Affairs
- Utrikesdepartementet, the Swedish Ministry of Foreign Affairs