A machine for making filter bags for infusion products starting from pieces of filter material each having two free ends and an intermediate portion , between each free end ( 1d and 1e ) and the intermediate portion having, respectively, two chambers containing a corresponding dose of product; the pieces advancing along a feed line ( A ) of the machine, comprising: - a first carousel for continuous rotary movement about a first axis of rotation and having at least a plurality of first operating stations positioned along, and continuously movable with, the first movement carousel , each first operating station being configured to retain and operate on a corresponding piece of filter material fed along at least one predetermined angular stretch of rotation of the first movement carousel , to obtain at least a lifting of the two chambers to a position side by side and erect, that is to say, positioned radially relative to the first axis of rotation; characterised by further comprising: - a second movement carousel positioned alongside the first carousel and rotating continuously about a second axis of rotation parallel to the first axis of rotation; the second carousel having a plurality of joining elements positioned along, and continuously movable with, the second carousel ; each joining element being connected to corresponding control devices configured for actuating, in a synchronised fashion with the corresponding rotations of the first and the second carousel and at least along a stretch of predetermined curved path, a succession of movements of the joining element to intercept the free ends of the piece of erected filter material, positioned on the operating station and joining them, towards one of the two chambers containing a dose of product. - a first carousel for continuous rotary movement about a first axis of rotation and having at least a plurality of first operating stations positioned along, and continuously movable with, the first movement carousel , each first operating station being configured to retain and operate on a corresponding piece of filter material fed along at least one predetermined angular stretch of rotation of the first movement carousel , to obtain at least a lifting of the two chambers to a position side by side and erect, that is to say, positioned radially relative to the first axis of rotation; characterised by further comprising: - a second movement carousel positioned alongside the first carousel and rotating continuously about a second axis of rotation parallel to the first axis of rotation; the second carousel having a plurality of joining elements positioned along, and continuously movable with, the second carousel ; each joining element being connected to corresponding control devices configured for actuating, in a synchronised fashion with the corresponding rotations of the first and the second carousel and at least along a stretch of predetermined curved path, a succession of movements of the joining element to intercept the free ends of the piece of erected filter material, positioned on the operating station and joining them, towards one of the two chambers containing a dose of product. - a second movement carousel positioned alongside the first carousel and rotating continuously about a second axis of rotation parallel to the first axis of rotation; the second carousel having a plurality of joining elements positioned along, and continuously movable with, the second carousel ; each joining element being connected to corresponding control devices configured for actuating, in a synchronised fashion with the corresponding rotations of the first and the second carousel and at least along a stretch of predetermined curved path, a succession of movements of the joining element to intercept the free ends of the piece of erected filter material, positioned on the operating station and joining them, towards one of the two chambers containing a dose of product. <EOS>