INTRODUCTION: Hypothermic circulatory arrest for adult aortic arch repair is still high-risk. Despite decades of clinical experience, significant practice variations exist around the world. These practice variations in hypothermic circulatory arrest may offer multiple opportunities to improve practice. The hypothesis of this study was that the current conduct of adult hypothermic circulatory arrest in Europe has significant variations that might suggest opportunities for risk reduction. METHODS: An adult hypothermic circulatory arrest questionnaire was developed and then administered at thoracic aortic sessions at international conferences during 2010 in Beijing and Milan. The data was collected, abstracted and analyzed. RESULTS: The majority of the 105 respondents were anesthesiologists based in Europe and China. The typical adult aortic arch repair in Europe was with hypothermic circulatory arrest at moderate hypothermia utilizing bilateral antegrade cerebral perfusion, typically monitored with radial arterial pressure and cerebral oximetry. Brain temperature was frequently measured at distal locations. The preferred neuroprotective agents were steroids, propofol and thiopental. CONCLUSIONS: The opportunities for outcome improvement in this emerging European paradigm of tepid adult aortic arch repair include nasal/tympanic temperature measurement and adoption of unilateral antegrade cerebral perfusion monitored with radial artery pressure and cerebral oximetry. The publication of an evidence-based consensus would enhance these practice-improvement opportunities.