The Serbian–Hungarian Baranya–Baja Republic (Hungarian: Baranya-Bajai Szerb-Magyar Köztársaság, Serbian: Српско-мађарска република Барања-Баја / Srpsko-mađarska republika Baranja-Baja) was a small, short-lived and Soviet-oriented state, proclaimed in Pécs on 14 August 1921, on occupied Hungarian territory during the peacemaking aftermath of the first World War, tolerated and fostered by the newly proclaimed Kingdom of Serbs, Croats and Slovenes.

[2] The area of southern Hungary was occupied by the Kingdom of Serbs, Croats and Slovenes' army and was administered by the people's administration from Novi Sad.

Following the defeat of Béla Kun's Hungarian Soviet Republic in the summer of 1919, many communist dissidents from Budapest, escaping from the "white terror" of Admiral Miklós Horthy, emigrated to Baranya, where Béla Linder, mayor of Pécs, gave them refuge.

Linder, the military attaché of the Hungarian Soviet Republic based in Vienna in Austria, became the mayor of Pécs in September 1920.

From 21–25 August 1921, the region was reintegrated into Hungary, represented by Commissioner Károly Soós Bádoki, as had been allocated at the Treaty of Trianon of 1920.