This article is a brief presentation of the political regimes, of the power organization and of the relations that exist between bodies of state power in different types of political regimes. Starting from the general classification of political regimes in democratic regimes and undemocratic regimes, the author presents, in turn, the essential elements of every political regime separately. The novelty of the work is given by a happy joint of the constitutional law notions with those of the political sociology field. It is noteworthy, in the end of the article, the approach, realistic as possible, of the issue of the political regimes imperfection, whatever their ideological and doctrinal orientation.