The non-discrimination obligation has existed since the twelfth century. It has been practiced since then, changing from a conditional to unconditional form with the passage of time. It became firmly applied unconditionally at the multilateral level in 1947 after the formation of the GATT trading system upon which several countries based their trading relations. In 1995 when the WTO was formed, the underlying principles of the GATT 1947 became part of the WTO trading system, including the non-discrimination obligation. When countries join the WTO they automatically become subject to the non-discrimination obligation. The ever increasing value of services and trade in the value of intellectual property has necessitated a look at the fundamental principles of world trade that countries have to adhere to in their trade relations. Incidentally, countries are not at the same level economically, hence one of the purposes of the WTO is to facilitate development in developing countries. Accordingly, this requires different application and/or interpretation of these fundamental principles in different situations, depending on the development level of each Member country. Amongst the five principles that underlie the international trading system, the non-discrimination principle is the focus of this study. The sustainability of the entire economic relations between WTO Member countries is dependent upon their fair compliance with this obligation. The obligation is found in Articles II and XVII of the GATS and Articles 3 and 4 of the TRIPS. The Membership of the WTO is made up of developed and developing countries. As a result of the fundamental nature of the obligation it is imperative that the scope and interpretation of this obligation, as developed by WTO adjudicating bodies, be analysed to determine if the obligation’s application and/or interpretation satisfies the above fundamental object and purpose of the multilateral system of trade. The intention here is at all times to show the importance that the non-discrimination obligation carries in international economic and legal interactions and how non-observance of this obligation would negatively affect relations between Member countries of the WTO.