The objective of the Amsterdam Acute Aneurysm Trial is to study the combined outcome of conventional emergency surgery versus endovascular treatment for ruptured abdominal aortic aneurysms. The design used was a multicenter randomized clinical trial conducted in two university hospitals and one teaching hospital in the Amsterdam region. The study included all patients with a ruptured abdominal aneurysm who were eligible for endovascular and conventional surgery. The primary end points were combined mortality and severe morbidity. The secondary end points were quality of life and cost-effectiveness. The background, design, and methods of this trial are presented, and the ethical and legal issues of this type of research are discussed.