The agreement on an international biosafety treaty in January 2000 marks an important achievement in reconciling trade and environmental interests. The Cartagena Protocol on Biosafety strengthens the right of importing nations to reject shipments of genetically modified organisms on grounds of environmental safety or risks to human health. Crucially, it acknowledges the precautionary principle within its environmental risk assessment procedure. However, the political compromise that led to the adoption of the Protocol failed to resolve several contentious issues including labelling, liability, and the relationship between the biosafety regime and the international trade order. This article traces the history of biosafety negotiations, analyses the Cartagena Protocol and assesses the future biosafety agenda.