The article focuses on kuršininkai ethnic group living in the Curonian Spit since 15th C. as an object of scientific investigations at the end of 19th C. and the beginning of the 20th C. My attention is paying also to the reasons which stimulated scientists interest to this small ethnic community cultural traditions in the German Empire, where the policy of ethnic minorities levelling was growing sharpat that time. I emphasize in this my article the importance of Franz Tetzner’s cultural perceptivity concerning kuršininkai ethnic culture transformations in the context of processes of modernisation and assimilation. It is very important to have a comprehensive information from Tetzner investigations on such ethnic traditions of already disappeared kuršininkai community at present times. This information helps us to understand much better the specific features of kuršininkai local identity (such as Latvian speaking at home, specific customs, fishery terms) and their ties with Prussian Lithuanians’ culture traditions (Evangelical Lutheran confession, Lithuanian language in the church and at school). The investigations from this my article have an idea to enrich particular research works on historical Prussian Lithuania region cultural heritage.