Background: The continuing shortfall of organs for transplantation has led to interest in Maastricht Category II (uncontrolled) Donation after Circulatory Death (DCD) organ donation. As preparation for a proposed pilot, this study aimed to explore the potential of uncontrolled DCD organ donation from patients presenting in cardiac arrest to the emergency department (ED) who are unsuccessfully resuscitated. Methods: We identified all patients who died in our ED following unsuccessful resuscitation after cardiac arrest who were aged between 16 years and 60 years, whose collapse was witnessed, in whom the paramedics arrived within 15 min, whose death in the ED was less than 2 h after their collapse, who were on the organ donation register and who arrived in the ED during the working week (Monday to Friday between 9:00 and 17:00). Results: During a 14-month period from 1 August 2008 to 30 September 2009, 564 patients had a cardiac arrest in the Lothian region. Four patients may have been eligible to participate in an uncontrolled DCD organ donation programme. Conclusions: Identifying potential organ donors in the ED who are unsuccessfully resuscitated from cardiac arrest may contribute to reducing the shortfall of organs for transplantation, although numbers are likely to be small. If such a programme was to be introduced during weekday working hours, there may be around four donors a year. However, even one additional donor per year from hospitals across the UK with an ED and a transplantation service would add considerably to the overall organ donation rate.