339th may refer to:
339th Aviation Detachment, United States Army Aviation Branch 339th Bombardment Group, unit of the New York Air National Guard 339th Bombardment Squadron, inactive United States Air Force unit 339th Fighter Group, unit of the United States Air Forces during World War II 339th Flight Test Squadron, United States Air Force unit 339th Infantry Regiment (United States), infantry regiment of the United States Army 339th Rifle Division (Soviet Union), formed in 1941 as a standard Red Army rifle division at Rostov-on-Don 339th Transportation Company (Direct Support), United States Army and Transportation Corps 339th Troop Carrier Squadron, component of the 419th Operations Group
See also 339 (number) 339, the year 339 (CCCXXXIX) of the Julian calendar 339 BC