In recent decades, in the context of the transformation of national states and the development of multi-level government, there has been an increase in ethnic/regional political parties in Europe. Ethno-regionalism in the CEE countries has a specific basis related to their imperial past, but despite the similarities, each country has special features concerning the strength of parties, their demands and development. The analysis of the most significant ethnic/regional parties in the CEE countries shows that the main factor affecting their strength is the ethnic structure of the population, especially if it is combined with intense ethnic identity, and the ethnic minority has a historical experience of autonomy/statehood. A favorable combination of these factors results in the stability of the electoral strength of ethnic parties, which makes them an important player in the political arena. Concerning the demands of ethnic parties, it has been confirmed that the localization of the respective ethnic minority has a significant effect. If it is in one administrative unit, it stimulates regionalist aspirations; if it dwells in some compactly located administrative units, an ethnic party usually promotes cross-regionalist demands to create a new region. Under conditions of dispersed localization of a minority, an ethnic party does not put forward regionalist claims.