Hinge for the opening and the closing of hinged doors of furniture units, including a first fixed body designed to be housed in a seat of a horizontal plane of the structure of a furniture unit, such as a base or a top, and a second movable body designed to be housed in a seat of a door of the furniture unit, to actuate the door during opening and closing by way of a movement mechanism including at least one lever or connecting rod connecting a pin placed on the fixed part of the hinge and a pin placed on the movable part, wherein the closing force of the door is determined by a spring, the spring acting, with a tilting action, on an extension of the connecting rod beyond the hinge pin.