Factor VIIa is a revolutionary new pharmaceutical that promises to change the anaesthesia and critical care approach to major trauma. It is an extremely potent pro-coagulant agent, and while it enables haemostasis at the site of tissue injury, it also has the possibility of producing life-threatening thromboembolic complications. New data regarding FVIIa use is published almost every month, leading to a rapidly evolving clinical understanding of the potential indications, and potential pitfalls, of off-label use. Determination of appropriate practice, including the ability to judge the risks and benefits of FVIIa therapy for individual cases, is still some years in the future, and will depend in large part on clinical trials which are just getting underway.