On 1 May 2004 the European Union (EU) underwent unprecedented enlargement, from 15 to 25 countries, increasing its population by 20% to over 450 million. Although EU law has limited specific competence in the area of health, its influence on other policy sectors such as agriculture, trade, and employment has wide ranging implications for health. Yet with the exception of provisions on communicable disease control and food safety, public health considerations have played little part in negotiations on EU accession. This paper argues for an intersectoral public health approach in the expanded EU. It reviews the legal basis for assessing the health impacts of policy in the EU and, using health impact assessment as a case study, it examines how well the new member states may be prepared to tackle intersectoral public health action within the constraints imposed by EU policy.