The paper deals with the institute of succession of states in the international law, specifically its poistion in the area of the international treaties. In the paper the notion of succession in the international law is analysed, as well as the succession of states in respect of the international treaties. The paper further describes the clean slate theory and the universal succesion theory applied in the area of succession of states in respect of international treaties. In the conclusion the paper deals with the application of The Vienna convention on Succession of States in Respect of Treaties and with perspectives for the future. The aim of the paper is to come to a draft of the legal regulation de lege ferenda which combines the elements of the theories listed above and reflects the needs of the state practice in the area of the international law conveniently by comparing the clean slate theory and universal succession.