When studying international customs law, researchers primarily associate its current development with the activities of two international organisations – the World Customs Organization (WCO) and the World Trade Organization (WTO). At the same time, contributions to its formation, codification and progressive development were made by other international organisations as well, whose legal status, history and outcomes of activities remain largely unexplored to this day. One such organisation was the International Union for the Publication of Customs Tariffs (Publication Union), which operated from 1891 to 2017. The aim of this article is to address existing gaps in the scholarly study of the contributions of this economic international organisation to the formation, codification and progressive development of international customs law, as well as its impact on national customs law. The article examines the prerequisites for the establishment, termination and results of activities of the Publication Union.