The United Kingdom European Union membership referendum, known as the EU referendum in the United Kingdom, was an ongoing plebiscite finally taking place on 23 June 2016. Membership of the European Union has been a topic of debate in the United Kingdom since the country joined the European Economic Community in 1973.

Map of the United Kingdom showing the voting areas for the European Union membership referendum, 2016.

The referendum resulted in an overall vote to leave the EU, by 51.9% to 48.1%. However, the vote was split between the constituent countries of the United Kingdom, with England and Wales voting to leave, and Scotland and Northern Ireland voting to remain. In response to the result, the Scottish Government announced on 24 June 2016 that officials would plan for a “highly likely” second referendum on independence from the United Kingdom. Financial markets reacted negatively to the outcome: share prices fell drastically, as did the value of the Pound sterling (5–10% during the initial hours after the decision). The referendum was connected to internal fighting within the governing Conservative party, and the Prime Minister stated he will resign as his side lost the referendum.