This paper analyses an important issue in Romanian and European historiography, that of the role played by the Sulina Quarantine in the growth of international rivalry at the Danube Mouth during the 1830s – early 1850s. My research, based in particular on unpublished archival sources from the Chancellery of the Governor of Bessarabia (The National Archive of the Republic of Moldova), aims to address this issue through the prism of the organisation and inclusion of the Sulina Quarantine in the cordon sanitaire of the Russian Empire at the Danube Mouths. This allows for some more insight on whether the establishment of the Sulina Quarantine was justified from a sanitary point of view and how high a priority it was for imperial Russia’s objectives at the Lower Danube.