This article examines the implications of a possible Brexit for the EU’s Common Agricultural Policy and agri-food sector. Five potential ways in which these implications might be felt are discussed: (1) implications for the future orientation of the CAP in the absence of the UK; (2) implications for the EU budget and the share devoted to the CAP; (3) implications for the future regulatory environment for EU farm and food businesses; (4) implications for agricultural research; and (5) implications for future EU trade and trade relationships. Because the UK is a net contributor to the EU budget, a net importer of agri-food products from the EU, and punches above its weight in research terms, its withdrawal would have broadly negative effects for the EU farm and food sector. Whether the absence of the UK’s voice in the Council of Ministers when discussing future agricultural, trade and regulatory policies would be counted as positive or negative depends on one’s policy preferences in these areas. For those advocating a market-oriented agricultural policy and a regulatory regime strongly anchored in science its withdrawal would be a loss.