Extruder screw (100; 100') for a multi-screw extruder for plastics extrusion, at least comprising: - a feed and metering zone (1; 1') for melting and homogenizing the plastic and an evacuation zone (2; 2') for discharging gaseous constituents and a compression and/or discharge zone (4; 4'), which comprises at least one single-screw section; - a multi-screw section (20; 20'), which has a plurality of planetary screws (30; 30') which are exposed on the outer circumference of the extruder screw (100; 100') at least over a part of their length; - a drive zone (3; 3'), in which the planetary screws (30; 30') engage, by means of a toothing (33; 33'), in an external toothing on a central shaft or in an internal toothing in a stator ring or in the inner wall of an extruder bore of the multi-screw extruder; characterized - in that the feed and metering zone (1; 1') extends into the multi-screw section (20; 20') in that the single-screw section transitions into the multi-screw section by means of a cone portion, wherein the cone portion and a planetary screw housing adjoining it form a first longitudinal portion of the multi-screw section, - in that the cone portion (21; 21') is formed at the start of the multi-screw section (20; 20'), said cone portion having at least one planetary screw bore (22; 22') per planetary screw (30; 30'); - in that the planetary screw bores continue in flow channels which lie within the planetary screw housing, and in that the planetary screws therein are completely enveloped by the planetary screw housing over a partial length, - in that a length proportion of the planetary screws which is larger than the first partial length is exposed in the adjoining degassing zone in that said length proportion is not enveloped by the planetary screw housing. - a feed and metering zone (1; 1') for melting and homogenizing the plastic and an evacuation zone (2; 2') for discharging gaseous constituents and a compression and/or discharge zone (4; 4'), which comprises at least one single-screw section; - a multi-screw section (20; 20'), which has a plurality of planetary screws (30; 30') which are exposed on the outer circumference of the extruder screw (100; 100') at least over a part of their length; - a drive zone (3; 3'), in which the planetary screws (30; 30') engage, by means of a toothing (33; 33'), in an external toothing on a central shaft or in an internal toothing in a stator ring or in the inner wall of an extruder bore of the multi-screw extruder; characterized - in that the feed and metering zone (1; 1') extends into the multi-screw section (20; 20') in that the single-screw section transitions into the multi-screw section by means of a cone portion, wherein the cone portion and a planetary screw housing adjoining it form a first longitudinal portion of the multi-screw section, - in that the cone portion (21; 21') is formed at the start of the multi-screw section (20; 20'), said cone portion having at least one planetary screw bore (22; 22') per planetary screw (30; 30'); - in that the planetary screw bores continue in flow channels which lie within the planetary screw housing, and in that the planetary screws therein are completely enveloped by the planetary screw housing over a partial length, - in that a length proportion of the planetary screws which is larger than the first partial length is exposed in the adjoining degassing zone in that said length proportion is not enveloped by the planetary screw housing.