A system for stapling sausage casings, combining - a succession of staples which are juxtaposed and related to each other in a separable manner, two legs facing each other and a connection bridge between the aforementioned legs being distinguished in each staple; and - a stapler mechanism with a staple supply channel having an inlet end and an outlet end and that is determined by at least one rear wall and two side closing walls; an anvil placed underneath and close to the outlet end of the supply channel; and a punch slidable along the supply channel, all of this suitable so that a staple can be introduced into the supply channel through the inlet end and be pushed by the punch in the sliding thereof towards the outlet end and towards the anvil against which the aforementioned staple is flattened and the legs thereof shaped into closing, the system being characterised in that the aforementioned rear wall of the supply channel extends beyond the inlet end along a staple receiving area determining a rear receiving wall for the arrangement therein of the first staple of the succession of staples, at least this rear receiving wall having a protrusion formation which extends in the same direction that the supply channel extends and which determines a sort of rail for accommodating the staple and guiding it in the path thereof in the direction to the feeding channel, for which reason said protrusion formation has a width related to the separation between the legs of the staple in one area close to the connection bridge thereof, said staple being prevented or limited from rotation in the receiving area and in the movement thereof towards the supply channel by the inner face of the legs contacting sides of the protrusion formation and in that, seen in plan view, and at least on the front side which is facing the rear receiving wall when the staples are arranged in the aforementioned receiving area, the body of the staples has a groove with an outline and dimensions sufficient to prevent mechanical interference with the protrusion formation which would alter the alignment of the staple with the punch and the aforementioned supply channel. - a succession of staples which are juxtaposed and related to each other in a separable manner, two legs facing each other and a connection bridge between the aforementioned legs being distinguished in each staple; and - a stapler mechanism with a staple supply channel having an inlet end and an outlet end and that is determined by at least one rear wall and two side closing walls; an anvil placed underneath and close to the outlet end of the supply channel; and a punch slidable along the supply channel, all of this suitable so that a staple can be introduced into the supply channel through the inlet end and be pushed by the punch in the sliding thereof towards the outlet end and towards the anvil against which the aforementioned staple is flattened and the legs thereof shaped into closing, the system being characterised in that the aforementioned rear wall of the supply channel extends beyond the inlet end along a staple receiving area determining a rear receiving wall for the arrangement therein of the first staple of the succession of staples, at least this rear receiving wall having a protrusion formation which extends in the same direction that the supply channel extends and which determines a sort of rail for accommodating the staple and guiding it in the path thereof in the direction to the feeding channel, for which reason said protrusion formation has a width related to the separation between the legs of the staple in one area close to the connection bridge thereof, said staple being prevented or limited from rotation in the receiving area and in the movement thereof towards the supply channel by the inner face of the legs contacting sides of the protrusion formation and in that, seen in plan view, and at least on the front side which is facing the rear receiving wall when the staples are arranged in the aforementioned receiving area, the body of the staples has a groove with an outline and dimensions sufficient to prevent mechanical interference with the protrusion formation which would alter the alignment of the staple with the punch and the aforementioned supply channel.