The Department of National Security or OZNA (Serbo-Croatian: Odjeljenje za zaštitu naroda or Odeljenje za zaštitu naroda, Одељење за заштиту нaрода; Macedonian: Одделение за заштита на народот; Slovene: Oddelek za zaščito naroda) was the security agency of Yugoslavia that existed between 1944 and 1946.
OZNA was founded on May 13, 1944 under the leadership of Aleksandar Ranković (nom de guerre Marko), a top member of the Politburo until his downfall in 1965/66, and a close associate of Josip Broz Tito.
Until OZNA was established, intelligence and security tasks were carried out by several organizations. In spring 1944, the tasks were carried out by the Section for Protection of People in central and western Bosnia, part of Croatia, and Vojvodina; the centers of territorial intelligence in Croatia, Vojvodina and Montenegro; the intelligence division of the Internal Affairs Section within the Slovene National Liberation Committee presidency in Slovenia; and the intelligence service of the partisan detachments in Central Serbia, Macedonia, and Kosovo.