Method for producing a plastic hollow profile with at least one hollow chamber provided with a foamed body, with at least the following method steps: - melting a first thermoplastic material in a main extruder and feeding the melt to the die opening of a main die for forming the plastic hollow profile; - melting a second thermoplastic polymer, which is expandable, in a coextruder and feeding the melt to an additional die for forming the foamed body; - discharging the expanding second polymer into the hollow chamber; - cooling and calibrating the extruded plastic hollow profile; characterized - in that, before being discharged into the hollow chamber, the melt of the second polymer is fanned out in the additional die under pressure at an intermediate die plate with multiple part-channels, which respectively extend up to a die opening, - in that the melt is conducted via the die openings, which are distributed over the cross section of the hollow chamber to be filled, into a foaming chamber, which extends in the take-off direction of the plastic hollow profile over a length L2 within the already formed hollow chamber of the plastic hollow profile and has a narrowing cross section, - in that an abrupt expansion of the individual strands of the melt emerging from the intermediate die plate takes place in the foaming chamber; - in that the individual strands are reunited in the foaming chamber by a conical form of the foaming chamber to form a foam compound; - and in that the expanding second polymer is discharged through the discharge opening of the foaming chamber, which is reduced in cross section in comparison with the hollow chamber, into the hollow chamber and expands therein. - melting a first thermoplastic material in a main extruder and feeding the melt to the die opening of a main die for forming the plastic hollow profile; - melting a second thermoplastic polymer, which is expandable, in a coextruder and feeding the melt to an additional die for forming the foamed body; - discharging the expanding second polymer into the hollow chamber; - cooling and calibrating the extruded plastic hollow profile; - in that, before being discharged into the hollow chamber, the melt of the second polymer is fanned out in the additional die under pressure at an intermediate die plate with multiple part-channels, which respectively extend up to a die opening, - in that the melt is conducted via the die openings, which are distributed over the cross section of the hollow chamber to be filled, into a foaming chamber, which extends in the take-off direction of the plastic hollow profile over a length L2 within the already formed hollow chamber of the plastic hollow profile and has a narrowing cross section, - in that an abrupt expansion of the individual strands of the melt emerging from the intermediate die plate takes place in the foaming chamber; - in that the individual strands are reunited in the foaming chamber by a conical form of the foaming chamber to form a foam compound; - and in that the expanding second polymer is discharged through the discharge opening of the foaming chamber, which is reduced in cross section in comparison with the hollow chamber, into the hollow chamber and expands therein.