Events from the year 2003 in the European Union.

Incumbents

• Commission President - Romano Prodi
• Council Presidency - Greece (Jan-Jun) and Italy (July-Dec)
• Parliament President - Pat Cox, ELDR Party
• High Representative - Javier Solana, Socialists

Events

• 1 January: Greece takes over the Presidency of the European Union.
• 1 February: Nice Treaty enters into force.
• 8 March: Referendum in Malta approves joining the Union.
• 23 March: Referendum in Slovenia approves joining the Union.
• 9 April: European Parliament approves the 2004 enlargement.
• 12 April: Referendum in Hungary approves joining the Union.
• 16 April: Accession treaties of 2004 entrants is signed in Athens.
• 11 May: Referendum in Lithuania approves joining the Union.
• 17 May: Referendum in Slovakia approves joining the Union.
• 8 June: Referendum in Poland approves joining the Union.
• 14 June: Referendum in the Czech Republic approves joining the Union.
• 1 July: Italy takes over the Presidency of the European Union.
• 14 September: Referendum in Sweden rejects joining the eurozone.
• 14 September: Referendum in Estonia approves joining the Union.
• 4 October: ICG convened in Rome to finalise the European Constitution.