The development of maritime transport at the turn of the 19th and 20th centuries contributed to the international unification of maritime law with regard to shipboard privileges and maritime mortgage. The need to harmonize the regulations resulted from the necessity of real assurance for creditors to satisfy their claims, because the diversity of regulations of individual states, the number of maritime privileges was established under different legal systems and the hierarchy of their application limited the significance of the maritime mortgage institution. The content of international regulations has become the basis for shaping Polish regulations regarding the above-mentioned maritime law institutions. These, however, were created only at the beginning of the 1960s, hence the rich literature of the subject mainly concerns the period from the turn of the 20th and the 21st century. The issue of maritime privilege institutions in the interwar period has so far only been signalled, therefore, this publication aims to provide a comprehensive discussion of the issue.