On 8th May 2017, one of the arm of the British scientific establishment, the Royal Institution, has opened its famous lecture theatre to a debate about Brexit. Brexit is not about extricating the UK from the European scientific endeavour. And Brexit does not bring to an end many important aspects of the integrated European scientific projects. Today, it is not obvious, however, which strategies the UK–and the other EU 27 countries–could adopt to sustain as much as possible international collaborations and mobility. In this opinion piece, representatives of EuroScience argue that scientists need to raise their voices to guarantee their future and the future of our societies. Should all negotiation fail and the UK ends up with weakened relations with the EU 27, the authors argue, it remains to be seen whether the UK plan to strengthen relations and collaborations with the US, the Commonwealth and East-Asia will be an adequate substitute.