The article presents the Lithuanian interim constitution of 1990. This act had fundamental significance for the restitution of an independent Lithuanian state. The author presents the circumstances in which this act was adopted and highlights its most important features. He attempts to address the issue of what system of government the act introduced and to what extent it was a continuation (in a changed historical reality) of the solutions from the period of the Soviet Union, and to what extent it referred to the Western European constitutional tradition.