AD 3 or AD-3 may refer to:
A year of the 0s decade in the in the Julian calendar Salmson AD.3, an aircraft piston engines of the 1920s Adaridi AD 3, a Finnish experimental aircraft of the 1920s AD-3, the third production variant of the Douglas AD Skyraider aircraft One of the experiments running on the Antiproton Decelerator , a US Navy destroyer tender