International organisations are associations of countries which are founded on the basis of a contract, have theirown constitution and common institutions and posssess individuality separated from the one of the member states and are subjects of international law with the capacity of contract conclusion.The need for the institualisation of international cooperation is present in all the communinities where there are several countries that share certain connections, whether they are economical or cultural ones. The first traces of international cooperation can be found in ancient civilisations of Mesopotamia, China, Egypt, India, Greece and Rome, thus the reasearch about the history of development of international organisations could include all periods stretching from the beginnings of the first civilisations to the modern times.The period of the second half of the 19th century and the first half of the 20th century is considered to be the time when international organisations are starting to form their modern shape. Great social changes in all the segments of human life are starting to take place, the cooperation between countries which is conditioned by the development and the growth of industry and trade is intensifying and therefore the need for the regulation of that cooperation in a way that international relations are consciously being influenced upon and that measures for the improvment of those relations are being taken starts to occur.At the end of the World War I the first universal internationl organisation was founded, The League of Nations, whose main aim was to prevent the reoccurence of the horrors which befell Europe during the World war I. The League of Nations did not succeed in its primal goal, but it did pave the path for the other international organisations and in 1945 the greatest universal international organisation was founded, The United Nations, which is the nearest to the ideal of the universal international organisation.