The article discusses the evolution of the EC/EU’s status in the UN from the perspective of theoretical studies of the relations between intergovernmental international organisations. The first section is dedicated to an analysis of the literature that explains the general processes and determinants affecting the development of relations between international organisations and that, consequently, can be considered relevant theoretical literature in this field. In this context, the author highlights, among others, studies dedicated to the explication of various categories of determinants underlying the establishment and development of relations between international organisations, works explaining the determinants of cooperation and rivalry between international organisations and works explaining the relations in interorganisational networks. In the second section, the author discusses the most important monographs addressing, for example, issues im - portant for research on the relations between the EU and other intergovernmental international organisations. The third and fourth sections are devoted to the evolution of the EU’s status in the UN, including an analysis of the competences of the EEC and then the EC and the EU in the UN between 1974 and 2011, followed by a discussion of the most important changes introduced in this regard under United Nations General Assembly Resolution 65/276 of 3 May 2011. In conclusions, the author seeks to evaluate the changes in the EU’s status in the UN compared to, among others, the status, efforts and expectations of other non-state participants of international relations, including non-governmental organisations, in the context of the development of their relations with the UN.