AP3 may refer to one of the following:

• The ABC Model of Flower Development
• Andrew Pendelton III, an American professional wrestler

AP-3 may refer to:

• USS Hancock (AP-3), a transport ship acquired by the United States Navy in 1902 which saw service during World War I
• AP-3C Orion, a variant of the P-3C Orion maritime patrol aircraft used by the Royal Australian Air Force

• Universitity of Stuttgart
• University administration
• University administrator
• University Admission Index
• University Admissions Index
• University Affiliated Research Center
• University Air Squadron
• University alliance in Taiwan
• University alliances in Taiwan
• University and college admission
• University and Colleges Athletic Association
• University Arboretum at California State University, Sacramento
• University at Albany, SUNY
• University at Buffalo
• University at Buffalo Law School
• University at Buffalo Stadium
• University at Graz
• University Athletic Association
• University Athletic Association of the Philippines
• University Athletics Association of the Philippines (UAAP)
• University at Stony Brook
• University Avenue
• University Avenue (Minneapolis–Saint Paul)
• University Avenue (Toronto)
• University Boat Race