The invention relates to a sectional door comprising a door leaf that can be displaced between a closed position and an open position along a path prescribed by a guide rail assembly. Said guide rail assembly comprises two approximately parallel guide rails each having two approximately linear sections that are interconnected by an arched section. The aim of the invention is to improve a sectional door of this type. To this end, an additional guide assembly, which is preferably mounted between the guide rails while serving to guide the movement of the door leaf along the arched section of the prescribed path, is assigned to the door leaf.