Abstract: An apparatus for mounting valve bags on the filling spouts of machines which fill the bags with finely-grained material, e.g. cement. The bags are folded flat and are stacked in a bag storage container. A feed mechanism removes the topmost bag from the stack and positions it in the path of a pivotal arm. The arm is provided with rollers which correctly position and shape the top of the bag and open the valve therein. Lever-actuated clamps hold the bag while it is mounted on the filling spout of the filling machine.In a variant of the invention, the bag feeding mechanism rotates and occupies successive stations, one of which is traversed by the pivotal arm which removes the bag from the mechanism for mounting on the filling spout.