Nearly 3.4 million people are eligible to vote for new Bosniak, Croat and Serb members of the country's inter-ethnic presidency as well as deputies in the national, regional and cantonal assemblies.
Voters in Bosnia and Herzegovina have headed to the polls for general elections.
Polls opened at 7:00 am local time (0500 GMT) on Sunday and will close at 7 pm local (1700 GMT).
The first official results are expected at midnight (2200 GMT).
People are casting ballots in a dizzying number of contests, including for the three members of Bosnia's tripartite presidency, the deputies of the central parliament and a string of local races.
Bosnia Herzegovina's political structure is often dubbed as one of the most complicated in the world.
A total of nine candidates will compete in the election for the Bosniak, Serb, and Croat members of the Presidential Council.
This is the least number of candidates since 2002 when the four-year mandate was introduced.
That year, a total of 35 candidates competed for membership, with the number rapidly falling with each election since then.
This year, Bakir Izetbegovic, leader of the largest Bosniak (Bosnian Muslim) Party of Democratic Action (SDA) is running for the Bosniak presidency member.
He is seen in a tight race with Denis Becirovic of the Social Democratic Party (SDP) , whose bid is supported by 11 civic-oriented opposition parties.
With little to no polling data available, analysts say incumbents that have dominated the political scene are likely to win many of the races.
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But some polls have suggested that separatist pro-Russian leader Milorad Dodik, who is running for the Serb Republic's president, is facing strong competition from opposition economist Jelena Trivic.
The Croat parties have warned they may block the formation of government after the vote if moderate Zeljko Komsic wins the job of the Croat presidency member.
They say his victory could only be based on votes by majority Bosniaks and that they will not regard him as the legitimate Croat representative.
The Balkan state has been governed by an administrative system created by the 1995 Dayton Agreement that succeeded in ending the war in the 1990s but largely failed in providing a framework for the country's political development.
Bosnia remains partitioned between a Serb entity - the Republika Srpska (RS) - and a Muslim-Croat federation connected by a central government.