A method for producing a rod for substantially cylindrical articles of the tobacco processing industry; each article comprising portions (4, 5) of different materials; the method comprising: a feeding step, during which a first material is fed, in a conveying direction along a first given path, through an insertion station and to a wrapping station; the first material having cavities arranged in succession in the conveying direction; an insertion step, during which a given amount of a loose material, in particular in the form of particles and/or fibres and/or granules, is inserted into the cavities in the insertion station, so as to form a strand; and a wrapping and stabilizing step, during which a strip is wrapped around the strand and stabilized around the strand itself in the wrapping station; wherein an insertion unit, which comprises a loading chamber to hold the given amount of loose material and an unloading device to unload the loose material from the loading chamber, is moved into the area of the first material, so that the unloading device faces one of the cavities; during the insertion step and the feeding step, the insertion unit is moved in the conveying direction along at least one coupling portion of the first given path, so that the unloading device is kept facing the respective cavity as the loose material is fed from the insertion unit into the cavity; the method being characterized by comprising, furthermore, a metering step, during which a transfer seat with a given volume is filled with said loose material, so as to obtain said given amount; and a loading step, during which the given amount of loose material is transferred from said transfer seat to the loading chamber. a feeding step, during which a first material is fed, in a conveying direction along a first given path, through an insertion station and to a wrapping station; the first material having cavities arranged in succession in the conveying direction; an insertion step, during which a given amount of a loose material, in particular in the form of particles and/or fibres and/or granules, is inserted into the cavities in the insertion station, so as to form a strand; and a wrapping and stabilizing step, during which a strip is wrapped around the strand and stabilized around the strand itself in the wrapping station; wherein an insertion unit, which comprises a loading chamber to hold the given amount of loose material and an unloading device to unload the loose material from the loading chamber, is moved into the area of the first material, so that the unloading device faces one of the cavities; during the insertion step and the feeding step, the insertion unit is moved in the conveying direction along at least one coupling portion of the first given path, so that the unloading device is kept facing the respective cavity as the loose material is fed from the insertion unit into the cavity; the method being characterized by comprising, furthermore, a metering step, during which a transfer seat with a given volume is filled with said loose material, so as to obtain said given amount; and a loading step, during which the given amount of loose material is transferred from said transfer seat to the loading chamber.