MEP elections around the continent
The 751 seats are allocated in proportion to each country's population.
Voters in most EU countries are going to the polls in the fourth and final day of European elections. Germany, France, Poland and Spain are among the 21 countries voting for members of the European Parliament.
Elections have already taken place in seven EU member states, including Malta, the UK, the Netherlands and Latvia. Results will be announced after the last poll closes at 22:00 Central European Time.
The parliament's powers have expanded since the last election in 2009.
MEPs now negotiate legislation with national government ministers in what is called “co-decision”, before parliament votes on the laws.
They have a say on budget areas including agriculture and regional aid.
Greece, which had to be bailed out by the EU and other lenders over its debts, was one of the first countries to open polling stations on Sunday.
Voting is compulsory in Greece, where there is widespread resentment at the austerity enforced as a condition for the bailout.
In Belgium, voters are also choosing a new national government. The last election left the country, which hosts the EU capital Brussels, without a government for 18 months, until a three-party coalition could be put together.
Croatians are voting in their second EU election in just over a year. Croatia held early elections in April 2013, in anticipation of joining the EU on 1 July.
The 751 seats are allocated in proportion to each country's population.
The vote will affect the lives of the EU's 500 million citizens, and the chamber has much more power than it used to.
It is a co-legislator, with government ministers from the EU's 28 member-states, in most policy areas.
One of the first tasks of the incoming parliament will be to elect a new president of the European Commission, the EU's executive body.