A cutting assembly for a harvester comprising: a conveyor drum which is mounted rotatably and which distributed around an outer periphery has a plurality of radially outwardly projecting conveyor elements which together define an envelope cylinder of the conveyor drum, a guide element which extends over a length of the envelope cylinder and in an arcuate shape around a sector of an outer periphery of the envelope cylinder in such a way that a conveyor passage for crop is formed between the outer periphery of the conveyor drum and the guide element, and at least one cutting unit having an elongate cutting blade which in a cutting position thereof extends from a side of the guide element, that faces away from the conveyor drum alongside through an opening in the guide element into the conveyor passage to cut up the crop in cooperation with the conveyor elements, wherein in its cutting position the cutting blade at a first longitudinal end thereof, that projects into the conveyor passage, engages into the opening in the guide element so that the first longitudinal end of the cutting blade is supported at both sides by the guide element in a longitudinal direction of the conveyor drum and the cutting blade at a first longitudinal side thereof, that faces towards the conveyor drum, has a cutting edge which projects into the conveyor passage and which is of a predetermined length dimension along the first longitudinal side, and wherein the cutting blade engages along the longitudinal dimension of the cutting edge into the opening in the guide element so that the cutting blade is supported at both sides by the guide element along the longitudinal dimension of the cutting edge in the longitudinal direction of the conveyor drum, characterised in that the cutting blade has a second longitudinal side which faces away from the conveyor drum and which in the cutting position of the cutting blade is disposed completely on the side of the guide element, that faces away from the conveyor drum, and a second cutting edge is provided at the second longitudinal side of the cutting blade in relation to a longitudinal centre line thereof in mirror-symmetrical relationship with the cutting edge which projects into the conveyor passage, wherein the cutting blade has a second longitudinal end which is on the side of the guide element, that faces away from the conveyor drum, and the cutting blade starting from an intermediate position between its first and second longitudinal ends (41a, 41b) towards its first longitudinal end as viewed in the longitudinal direction of the conveyor drum defines a rectangular shape whose long sides are respectively contained in one of the two longitudinal sides (42a, 42b) of the cutting blade. a conveyor drum which is mounted rotatably and which distributed around an outer periphery has a plurality of radially outwardly projecting conveyor elements which together define an envelope cylinder of the conveyor drum, a guide element which extends over a length of the envelope cylinder and in an arcuate shape around a sector of an outer periphery of the envelope cylinder in such a way that a conveyor passage for crop is formed between the outer periphery of the conveyor drum and the guide element, and at least one cutting unit having an elongate cutting blade which in a cutting position thereof extends from a side of the guide element, that faces away from the conveyor drum alongside through an opening in the guide element into the conveyor passage to cut up the crop in cooperation with the conveyor elements, wherein in its cutting position the cutting blade at a first longitudinal end thereof, that projects into the conveyor passage, engages into the opening in the guide element so that the first longitudinal end of the cutting blade is supported at both sides by the guide element in a longitudinal direction of the conveyor drum and the cutting blade at a first longitudinal side thereof, that faces towards the conveyor drum, has a cutting edge which projects into the conveyor passage and which is of a predetermined length dimension along the first longitudinal side, and wherein the cutting blade engages along the longitudinal dimension of the cutting edge into the opening in the guide element so that the cutting blade is supported at both sides by the guide element along the longitudinal dimension of the cutting edge in the longitudinal direction of the conveyor drum, characterised in that the cutting blade has a second longitudinal side which faces away from the conveyor drum and which in the cutting position of the cutting blade is disposed completely on the side of the guide element, that faces away from the conveyor drum, and a second cutting edge is provided at the second longitudinal side of the cutting blade in relation to a longitudinal centre line thereof in mirror-symmetrical relationship with the cutting edge which projects into the conveyor passage, wherein the cutting blade has a second longitudinal end which is on the side of the guide element, that faces away from the conveyor drum, and the cutting blade starting from an intermediate position between its first and second longitudinal ends (41a, 41b) towards its first longitudinal end as viewed in the longitudinal direction of the conveyor drum defines a rectangular shape whose long sides are respectively contained in one of the two longitudinal sides (42a, 42b) of the cutting blade.