Most favoured nation (MFN) treatment and national treatment (NT) are two standards usually related to the general principle of non-discrimination. However, while the MFN treatment was undoubtedly and clearly defined already during the negotiation of the General Agreement on Tariffs and Trade in previous works and judgements of various international bodies, the NT standard needed to be clarified. An additional reason to concentrate on NT rules is that their content and scope may influence trade more than the scope of MFN granted. The concept of NT is also subject to relatively rare analysis in comparison with other aspects of regional trade agreements’ (RTA) rules which overlap with WTO law. The aim of this article is to analyse the scope and wording of the NT standard in various RTAs concluded by the European Union. In particular, it inquiries into the extent to which the NT clause remains universal across its different regional trade agreements, and examines the reasons (and consequences) for the differences, if any, in its formulation.