The theme of this thesis is the historical development of consular law and its institutes, from the early beginnings of development to modern positive law of the 21st century. In the introductory part, the paper deals with the notion of consular law and consular relations, which emphasizes their importance in application between states, but also the functions that derive from it. Diplomatic law is compared with consular law through its historical aspects of development. After a conceptual elaboration, follows the historical development of consular law ranging from the old to the Middle Ages and the appointment of consuls on the occasion of the development of numerous trade colonies. The paper further deals with the consular development that occurred in the period between the Middle Ages and the period of the Second World War. Furthermore, the paper describes the second phase of the codification of consular law after the Second World War, and the adoption of two important conventions for international law: Vienna Convention on Diplomatic Relations from the year 1961 and the Vienna Convention on Consular Relations from 1963. The central part of the work deals with the establishment and development of consular relations and services, the opening of consulates, classification of heads of consulates, their powers and privileges as well as a number of other consular rights regulated in modern application. The essential features of consulates in international law and relations, as well as the structure of consular missions in the Republic of Croatia, are emphasized. The aim of this thesis is to show the importance of consular law in contemporary international law, through its historical development with the development of trade, economy, travel, tourism and other interstate activities.