The invention refers to a door with a door leaf consisting of one or more members that can swivel relative to each other, which is movable in a frame mounted on a building, guided on the side, from a vertical closed position into at least an approximately horizontal open position, where the door has a counterweight unit that is formed of at least one helical spring mounted on a horizontal pinion and that can be pre-tensioned by means of rotation, where the pinion is mounted directly on the door leaf with the helical spring. According to the invention, the pinion is mounted on the upper section of the door leaf in the closed state of the door.