Some 1.7 million eligible voters can answer with Yes or No to the referendum question that reads "Are you in favour of the law ratifying the arbitration agreement between the governments of Slovenia and Croatia, which was adopted by the Slovenian Parliament at its session of 19 April 2010, becoming valid?".
The acceptance of the border arbitration deal at the referendum would give the greenlight to the further implementation of what Prime Ministers Borut Pahor and Jadranka Kosor agreed in Stockholm on 4 November last year,
In the event that Slovenian reject the agreement, efforts aimed at the demarcation of the borderline would be brought back to the beginning.
The result of the referendum is binding on the authorities. A majority of the Yes answers will mean that the arbitration agreement is finally confirmed and that its prior ratification in the national parliament is valid.
The turnout is not a prerequisite for declaring the referendum's outcome valid.
On Sunday evening, the central election commission will announce the outcome of the voting of voters who were able to express their opinion on the matter from Tuesday to Thursday as they were not at their place of residence today.
Preliminary results will be announced on Monday and the final official results will be released on Tuesday.
During the four-week campaign, the Borut Pahor cabinet called on the Slovenians to confirm the agreement, while the Opposition lobbied for its rejection labelling the deal as detrimental to the Slovenian state interests.
In his efforts to persuade voters to support the deal, Prime Minister Borut Pahor has warned that the rejection of the document would push Slovenia into isolation and the international community would not understand such a move.
The border dispute has for some time obstructed Croatia's European Union membership bid.