Multiple-shaft extruder for performing an extrusion method, comprising - a housing, - at least two housing bores (5, 6), which are formed in the housing such as to be parallel to each other and to penetrate one another, - at least two shafts (7, 8), which are rotatably drivable about associated rotational axes (15, 16), the shafts (7, 8) being arranged concentrically in the housing bores (5, 6) and each having an input-end shaft end (9, 10) and an output-end shaft end (12, 13), - a plurality of treatment elements (23, 24, 26, 27) for the treatment of a plastic material to be processed, the treatment elements (23, 24, 26, 27) being non-rotationally arranged one behind the other on the at least two shafts (7, 8) in the direction of the respective rotational axis (15, 16) and being formed in a closely intermeshing manner, - a material inlet and a material discharge, which define a conveying direction of the plastic material in the housing, the treatment elements (23, 24, 26, 27) being configured such that the conveying direction of the plastic material runs from the output-end shaft ends (12, 13) to the input-end shaft ends (9, 10), wherein at least one treatment element (23, 26) is arranged on each of the shafts (7, 8) between an output-end housing end and the material inlet, the treatment element (23, 26) being configured such that the plastic material is conveyable in the conveying direction, and wherein at least one degassing zone (32, 35) with an associated degassing opening (39, 40) is formed between the output-end housing end and the material discharge, characterized in that the output-end shaft ends (12, 13) are mounted in the output-end housing end by means of output-end bearings (49 to 52) and are sealed by means of output-end seals (53, 54). - a housing, - at least two housing bores (5, 6), which are formed in the housing such as to be parallel to each other and to penetrate one another, - at least two shafts (7, 8), which are rotatably drivable about associated rotational axes (15, 16), the shafts (7, 8) being arranged concentrically in the housing bores (5, 6) and each having an input-end shaft end (9, 10) and an output-end shaft end (12, 13), - a plurality of treatment elements (23, 24, 26, 27) for the treatment of a plastic material to be processed, the treatment elements (23, 24, 26, 27) being non-rotationally arranged one behind the other on the at least two shafts (7, 8) in the direction of the respective rotational axis (15, 16) and being formed in a closely intermeshing manner, - a material inlet and a material discharge, which define a conveying direction of the plastic material in the housing, the treatment elements (23, 24, 26, 27) being configured such that the conveying direction of the plastic material runs from the output-end shaft ends (12, 13) to the input-end shaft ends (9, 10), wherein at least one treatment element (23, 26) is arranged on each of the shafts (7, 8) between an output-end housing end and the material inlet, the treatment element (23, 26) being configured such that the plastic material is conveyable in the conveying direction, and wherein at least one degassing zone (32, 35) with an associated degassing opening (39, 40) is formed between the output-end housing end and the material discharge,