Marginal regions of Slovakia are studied from the two points of view - as a consequence of the previous social-spatial development and as a consequence of the transformation process. The first part of the study is focused to the development and the content of the marginality as a term and to the indication of historical and contemporary factors of formation the marginal regions. Then the complexity of their potential and resources, which they dispose and enter to the transformation process of the society, is described. The developing unbalances of these regions are discussed. The social issues of the Slovak marginal regions are understood to be central in the set of their problems. The abilities of these regions for adaptation to the new developing trends, activation and effective utilization of their own potential ensuring the complex regional development are considerably complicated. In conclusions some possibilities of change the developing trajectory of these problematic regions are outlined.