Political extremism and state security, deliberations in the context of PolandTo main aim of this article is to show the problems of extremist political organizations (left and right) active in the Republic of Poland, and to give an answer to the question, if those groups can influence on the internal security of the state and use the terrorism in its actions. The knowledge of the rangę and methods of those groups, their views, allows properly assess and recognize the potential threat that those groups can bring to the security - first of all constitutional. By this we mean the state of socio-political relations in the country, which ensures the respect and effective protection of the mechanisms established by the political system and assigned values and rights.