This article studies the ‘national question’ and its importance in the Left thought and movement from a realistic and pragmatic perspective. It insists that during the history of this movement, the nationalistic reading on the Left thought even in main socialist countries led to confiscating Marxism in favor of the nationalistic interests, though it apparently emphasized on the internationalist slogans. And the theoreticians and pragmatic Marxist leaders of any country according to the different conditions and priorities had a special interpretation of Marxism. While in some third world countries, the oppressed nations’ nationalistic desires have been condemned by the Left organizations of the dominant nations as deviation from Marxism, to trivialize the national question. This climate affected some Kurdish Left parties so that they at first followed the romantic and idealistic leftists of the nations who don’t have the national question, but afterward with awareness of their theoretical and political mistakes, they tried to distance themselves from them and moved towards realism. So, the author seeks to answer, why it happened and what has its effects been on the Kurdistan politics? In this relation, the article in the different parts examines the importance of the national question and nationalism in the Marxist theories, the Left movement in Iran and Kurdistan totally, and Komala-Kurdistan Toilers Revolutionary Organization of Iran in particular.