The elections herald the end of a Serb revolt which broke out in spring 1991 and led to Europe's most violent conflict since 1945. The rebellion, backed by President Slobodan Milosevic of Serbia and his armed forces, was inspired partly by the Serbs' fear of persecution in a newly independent Croatia, and partly by the dream of hiving off Serb-populated parts of Croatia and forging a Greater Serbian state.
Nowadays, that dream lies in ruins, shattered by the crushing defeats which President Franjo Tudjman's army inflicted on the Serbs in the summer of 1995.
For the Serbs of eastern Slavonia, the future holds the prospect not of independence but of minority status in a country with a poor track record of promoting civil rights and protecting ethnic minorities.
About 120,000 Serbs live in eastern Slavonia, including tens of thousands who fled, or were driven out of, other Serb-held parts of Croatia during the offensives of 1995. According to officials in the United Nations transitional administration, which has supervised eastern Slavonia since January 1996, up to 25,000 Serbs may leave the region, fleeing across the Danube to Serbia, rather than wait for Croatia to take over in July.
The refugees are certain to include unrepentant extreme nationalists as well as policemen and paramilitary fighters implicated in war crimes. Yet such groups make up only a minority of eastern Slavonia's population, and the UN administrator, Jacques-Paul Klein, is confident that most ordinary Serbs will not abandon the region.
Vojislav Stanimirovic, a moderate who leads the Independent Serb Democratic Party, a bloc formed to contest Sunday's elections, agrees that a majority of Serbs will stay and try to build new lives. "They have little choice, since they have nowhere else to go. Serbia cannot help us much any more,"he said.
The chief UN human rights investigator in Croatia, Elisabeth Rehn, accused the Croatian authorities on Tuesday of persistent harassment of Serbs and warned that such actions could easily provoke an exodus from eastern Slavonia. In particular, she cited the burning down of houses belonging to Serbs who had tried to return to their homes in the Knin area of south- western Croatia.
With the bitter clarity of hindsight, many Serbs now see that President Milosevic did his kinsfolk in Croatia few favours when he incited their nationalist passions in 1991. They now have the worst of both worlds, encountering suspicion or hostility in Croatia and indifference or rejection in Serbia.
As happened in the Serb-populated suburbs of Sarajevo last year, Serb hardliners in eastern Slavonia are trying to provoke an exodus of ordinary Serbs by spreading rumours of imminent Croatian revenge attacks. Tens of thousands of Croat refugees, displaced from eastern Slavonia in 1991, are expected to resettle the region after July.
Many such Croats undoubtedly have harrowing memories of 1991. Few could ever forget the Serbs' ruthless destruction of the leafy Danube town of Vukovar and the subsequent massacre of Croat civilians.
Still, the Croat government has solemnly promised the UN and Western powers to protect the Serbs after eastern Slavonia's reintegration.
Whether Croatia will honour that promise will become clearer after the 5,000-strong UN force begins to leave eastern Slavonia in July.