The article explores the state of historical memory of the Grand Duchy of Lithuania during the XX century and the beginning of the XXI century. Previously the Grand Duchy of Lithuania was not an element of the historical memory of ordinary inhabitants of the Belarusian provinces. The memory of Lithuania was preserved only among the Polish residents of the region. Russian imperial scholars were interested in the history of the Grand Duchy of Lithuania, but they did not contribute to the formation of Belarusian view of the history. The formation of the Belarusian historical memory began quite late - at the turn of the late XIX - early XX centuries. At the beginning of the XX century, nationalists constructed the Belarusian image of the Grand Duchy of Lithuania, but after the revolution they emigrated. The historical memory of the Grand Duchy of Lithuania in the Belarusian society in the XX century was determined by the representation of this medieval state as Lithuanian, not Belarusian. During the period of Perestroika, emigrant stereotypes about the historical past began to penetrate into Belarus. After the collapse of the USSR, Belarusian intellectuals shaped a new view of the past. The Grand Duchy of Lithuania was presented as a Belarusian state. The idea of the medieval Lithuanian state as Belarusian became deeply ingrained at the early XXI century.