Extradition as a form of international mutual assistance in criminal matters is an important international legal instrument which value exceeds the bilateral relations between states and must be viewed in the context of strengthening and improving the international legal order. The creation of the legal basis for extradition, on the one hand, contributed substantially to enhancing cooperation of the states to suppress crime that violates international legal order, as well as national law, to ensure the inevitability of responsibility and punishment of the criminals, but on the other hand - ensured the development of rules and principles governing extradition and guarantee the rights of the individual in relation to extradition. In this article the author highlights the historical evolution, the essence and the importance of the institution of extradition through the doctrinal views and international regulations. Keywords: extradition, legal assistance in criminal matters, international treaty.