This paper analyzes the possible impact of TTIP's so-called regulatory cooperation on the implementation of the precautionary principle in the EU. The European Commission argues that regulatory cooperation will not impinge on the application of the precautionary principle because, first, it does not change the legislative framework of precautionary legislation and, second, the right to regulate will be safeguarded by the TTIPs horizontal chapters. On the contrary, I argue in this paper, that these guarantees are insufficient. Given the methodological and institutional constraints presented by the TTIP's institutional design, in the long run, regulatory cooperation will undermine the precautionary approach to regulation in the EU.