In January 2020 the UK left the European Union (EU), although a transition period extends EU rules/regulations until the end of 2020 while a longer-term relationship agreement is negotiated. After almost 50 years of membership the UK economy is tightly integrated into that of the EU single market, and many UK laws and regulations have their origins in the EU, including those concerning tobacco. This paper provides an overview of potential implications of Brexit for UK tobacco control. We examine the key areas of the supply, cost, taxation, and regulation of tobacco products, and the impact of commitments in regards to the border between Ireland and Northern Ireland (NI). We find that Brexit provides an opportunity for improved tobacco control with potential for particular enhancements in the areas of taxation and product regulation. However, commitments in regards to NI mean these benefits either won’t extend to NI (which will continue to follow EU rules), or could lead to the whole UK having to follow most EU rules/regulations despite no longer being involved in the decision making process. The details of any future deal will be important, especially since virtually all UK tobacco products come from the EU, and hence would be subject to disruption/considerable new tariffs (i.e. taxation on imports) without a trade deal. We conclude that political will by the UK government to secure conditions which protect the UK’s world leading tobacco control measures will be key to whether Brexit helps or hinders tobacco control in the UK. In this regards the signs do not look at all good.