This article reviews the way in which the concept of precaution, as commonly referenced in EU law, is received in the WTO. It argues that precaution is not a principle, but one facet of a principle of making rational judgments based on available information, the other facet of which is “that risk is worth taking”. Systematically pursuing high cost measures in response to low risks is not a balanced approach, and has probably contributed to the scepticism with which the concept is viewed in the WTO. However, this article goes on to argue that, without needing to be a principle, precaution is the determining legal feature in the SPS Agreement, because, unlike in the European Union, there is no legislative harmonisation of SPS measures at international level, WTO Members being free to set their own appropriate level of protection. In fact, the concept of precaution is relevant in the context of many other WTO provisions and is in some respects quite close to the concept of subsidiarity. Notwithstanding this, the first WTO SPS cases, driven by regulatory exporters and an interventionist WTO, have excessively emphasised scientific issues, masking policy judgments that the WTO has neither the legal nor the political authority to sustain. The article concludes that the proper way forward necessitates closer political, legal and administrative links between the WTO and other relevant international organisations, and a move away from consensus in the latter.