This article examines different options for trade defence that would be open to the United Kingdom (UK) once it leaves the European Union (EU). It focuses on the role of trade defence instruments (TDIs) in the UK’s future trading future outside the bloc. If the UK leaves the EU without a deal, the country will be left to rely on WTO trading rules. The article looks at the UK’s continued membership to the WTO and the many hurdles the UK is likely to face in the WTO after Brexit, in particular in in issuing independent schedules for trade and services and identifying the UK’s own commitments independent of those of the EU. The article highlights the importance of TDIs to ensure that the UK is in a position to protect its industries from unfair competition after Brexit. It reviews recent proposals to establish a new trade authority and to build up the UK’s TDI capabilities. The article looks at trade defence options that would be available to the UK if it agreed to take part in a customs union with the EU, taking stock of the EU-Turkey customs union’s mixed record. Finally, it highlights that a competition law Brexit solution would leave no room for an independent trade defence.