As the essential objective of the GATT was to promote continuing liberalization of international trade, it was necessary to institute a procedure to enable the contracting parties to negotiate in this area. Therefore, rounds of multilateral trade negotiations (MTN) were instigated, during which the tariff concessions accorded by one party to another were generalized to all parties by means of the most-favoured-nation clause.

Overall, the earlier rounds of negotiations from 1947 to 1961 led to very substantial reductions in customs duties between the countries concerned.

The Kennedy Round, which lasted from 1964 to 1967, led to a further decrease in customs duties on a basis of a formula, and to the negotiation of an agreement on anti-dumping practices. But the contracting parties were not able to agree on the idea of a linear reduction in customs duties or on the problem of non-tariff* barriers which also constituted barriers to trade.

It was at the Tokyo Round (1973-1979) that most of the agreements on non-tariff barriers were eventually signed: technical barriers to trade, government procurement, subsidies, customs valuation, import licences and anti-dumping practices.