Regulating risks in the face of scientific uncertainty poses a particular challenge to policy-makers. Such problems are amplified when decisions are taken in a multi-level framework of supranational governance. The genetically modified organism (GMO) regulation in the European Union constitutes an especially salient issue of risk governance in a multi-lateral arena, as the topic is politically highly visible and decision-making is slow and contested. Furthermore, as authority is dispersed among multiple actors, European risk governance is in need of adequate mechanisms ensuring that decision-makers justify and account for their behavior. While legitimacy aspects of GMO governance have widely been examined, accountability relations within the field of GMO risk governance have hitherto only weakly been explored. Hence, this paper analyzes the question of who can be held accountable under the complex system of supranational risk governance. This paper claims that mere adherence by actors to the regulatory pr...