On 16 April 2003 in Athens, the 15 existing Members of the European Union and the 10 acceding countries — Cyprus, the Czech Republic, Estonia, Hungary, Latvia, Lithuania, Malta, Poland, Slovakia and Slovenia — signed the Treaty on their accession to the Union.
An 16 Aibreán san Aithin, shínigh 15 Ballstát reatha an Aontais Eorpaigh agus na 10 tir aontacha: Poblacht na Seice, an Eastóin, an Chipir, an Laitvia, an Liotuáin, an Ungáir, Malta, an Pholainn, an tSlóivéin, agus an tSlóvaic an Conradh maidir lena n-aontachas leis an Aontas.