In international economic relations and international politics, most favoured nation (MFN) is a status or level of treatment accorded by one state to another in international trade. The term means the country which is the recipient of this treatment must nominally receive equal trade advantages as the "most favoured nation" by the country granting such treatment (trade advantages include low tariffs or high import quotas). In effect, a country that has been accorded MFN status may not be treated less advantageously than any other country with MFN status by the promising country.

There is a debate in legal circles whether MFN clauses in bilateral investment treaties include only substantive rules or also procedural protections. The members of the World Trade Organization (WTO) agree to accord MFN status to each other. Exceptions allow for preferential treatment of developing countries, regional free trade areas and customs unions. Together with the principle of national treatment, MFN is one of the cornerstones of WTO trade law.

"Most favoured nation" relationships extend reciprocal bilateral relationships following both the General Agreement on Tariffs and Trade (GATT) and WTO norms of reciprocity and non-discrimination. In bilateral reciprocal relationships a particular privilege granted by one party only extends to other parties who reciprocate that privilege, while in a multilateral reciprocal relationship the same privilege would be extended to the group that negotiated a particular privilege. The non-discriminatory component of GATT/WTO applies a reciprocally negotiated privilege to all members of GATT/WTO without respect to their status in negotiating the privilege.

Most favoured nation status is given to an international trade partner to ensure non-discriminatory trade between all partner countries of the WTO. A country which provides MFN status to another country has to provide concessions, privileges, and immunity in trade agreements. It is the first clause in the GATT.

Under rules of WTO, a member country is not allowed to discriminate between trade partners and if a special status is granted to one trade partner, the country is required to extend it to all members of WTO. In a nutshell, MFN is a non-discriminatory trade policy as it ensures equal trading among all WTO member nations rather than exclusive trading privileges.