Mother tongue is one of the most important aspects of preserving identity of national or ethnic minority. Being in force since 2005 the Law on National and Ethnic Minorities and Regional Language minorities in Poland secures the right to preserve and maintain their language and to introduce it as an assistant language in municipalities. In the Opole province this refers to the German language, which also in the whole country dominates in teaching minority languages. Analysis of statistical data on the size of the German minority in Poland tends to reflect on the double meaning of the German language in the Opole Silesia. Is learning German as a minority language, fulfil such a role? To what extent German is ‘sui generis’ and to what extent „lingua franca” in the Opole Silesia? To answer this questions, the Education Information System data, the data of the National Population and Housing Census 2002 and 2011, as well as the statements of representatives of German minority were analysed.