Economic and social changes in the last two decades reduced the grazing animal systems more or less to the nature reservation areas. The main objective of these grazing systems on these areas is the preservation of natural treasures herited from the past. Beside that, grazing systems have social (employment) and economic (production) roles as well in some areas of the country. In this paper connections between sheep grazing and the maintenance of different grassland associations of Hungary are investigated from the point of nature reservation friendly farming systems. In general sheep grazing have more positive effects on nature reservation grasslands than its negative effects. It is not difficult to identify the negative effects and to apply proper practical methods avoiding or reducing these effects. Sheep grazing is a proper tool to handle the fragmentation of some of the national grassland areas so it must be kept on as a critical method in the natura friendly farming practices.