The European Union (EU) Mass Casualties and Health (MASH) project that ran between 2008 and 2010 was designed to study the management of mass casualties from chemical and radiological releases and associated health implications. One area of study for this project concerned arrangements within EU Member States for the management of mass casualties following a chemical release. This was undertaken via a confidential online questionnaire that was sent to selected points of contact throughout the EU. Responses were obtained from 18 states from respondents holding senior positions in chemical planning and incident response. Information gathered shows a lack of uniformity within the EU about the organization of responses to chemical releases and the provision of medical care. This article presents the overall findings of the study demonstrating differences between countries on planning and organization, decontamination, prehospital emergency medical responses, clinical diagnoses, and therapy and aftercare. Although there may be an understandable reluctance from national respondents to share information on security and other grounds, the findings, nevertheless, revealed substantial differences between current planning and operational responses within the EU states for the management of mass chemical casualties. The existing international networks for response to radiation incidents are not yet matched by equivalent networks for chemical responses yet sufficient information was available from the study to identify potential deficiencies, identify common casualty management pathways, and to make recommendations for future operations within the EU. Improvements in awareness and training and the application of modern information and communications will help to remedy this situation. Specialized advanced life support and other medical care for chemical casualties appear lacking in some countries. A program of specialized training and action are required to apply the findings revealed by the MASH study into a unified cross-border emergency medical response.