Relations between the European Union (EU) and Turkey were established in 1959, and the institutional framework was formalized with the 1963 Ankara Agreement. Although not a member state of the European Union, Turkey is one of the EU's main partners and both are members of the European Union–Turkey Customs Union. Turkey borders two EU member states: Bulgaria and Greece. While Turkey officially has diplomatic relations with 26 EU member states, it does not have diplomatic relations with 1 EU member state (Cyprus).
Turkey has been an applicant to accede to the EU since 1987. In 1999, Turkey gained candidate status to become a member of the EU. Accession negotiations were started in 2005, but have been stalled since 2016. EU–Turkey relations became strained following the 2016 coup attempt.