The Bijeljina massacre involved the killing of civilians by Serb paramilitary groups in Bijeljina on 1–2 April 1992 during the dawn of the Bosnian War. The majority of those killed were Bosniaks (or Bosnian Muslims). Members of other ethnicities were also killed, such as Serbs deemed disloyal by the local authorities. The killing was committed by a local paramilitary group known as Mirko's Chetniks and by the Serb Volunteer Guard (SDG, also known as Arkan's Tigers), a Serbia-based paramilitary group led by Željko Ražnatović (aka Arkan). The SDG were under the command of the Yugoslav People's Army (JNA), which was controlled by Serbian President Slobodan Milošević.

In September 1991, Bosnian Serbs had proclaimed a Serbian Autonomous Oblast with Bijeljina as its capital. In March 1992, the Bosnian referendum on independence was passed with overwhelming support from Bosniaks and Bosnian Croats, although Bosnian Serbs either boycotted it or were prevented from voting by Bosnian Serb authorities. A poorly organized, local Bosniak Patriotic League paramilitary group had been established in response to the Bosnian Serb proclamation. On 31 March, the Patriotic League in Bijeljina was provoked into fighting by local Serbs and the SDG. On 1–2 April, the SDG and the JNA took over Bijeljina with little resistance; murders, rapes, house searches, and pillaging followed. These actions were described as genocidal by the historian Professor Eric D. Weitz of the City College of New York. Professor Michael Sells of the University of Chicago concluded that they were carried out to erase the cultural history of the Bosniak people of Bijeljina.

Around 3 April, Serb forces removed the bodies of those massacred in anticipation of the arrival of a Bosnian government delegation tasked with investigating what had transpired. The International Criminal Tribunal for the former Yugoslavia (ICTY) and the Serbian War Crimes Prosecutor's Office were able to verify between 48 and 78 deaths. Post-war investigations have documented the deaths of a little over 250 civilian of all ethnicities in the Bijeljina municipality during the course of the war. After the massacre, a campaign of mass ethnic cleansing of non-Serbs was carried out, all mosques were demolished, and nine detention camps were established. Many deaths in Bijeljina were not officially listed as civilian war victims and their death certificates claim they "died of natural causes."

As of December 2014, local courts had not prosecuted anyone for the killings, and no members of the SDG had been prosecuted for any crimes the unit carried out in Bijeljina or elsewhere in Croatia or Bosnia and Herzegovina. Milošević was indicted by the ICTY and charged with carrying out a genocidal campaign that included Bijeljina and other locations, but died during the trial. Republika Srpska leaders Biljana Plavšić and Momčilo Krajišnik were convicted for the deportations and forcible transfers in the ethnic cleansing that followed the massacre. Radovan Karadžić, the former President of Republika Srpska, was convicted for the massacre and other crimes against humanity committed in Bijeljina. At the end of the war, fewer than 2,700 Bosniaks still lived in the municipality from a pre-war population of 30,000. The Serbs of Bijeljina celebrate 1 April as "City Defense Day", and a street in the city has been named after the SDG.