Abstract: A machine for manufacturing herringbone-pleated structures of a type particularly suitable for use in cylindrical or flat filter elements. The machine includes consecutive feeding forming and bunching components by which a continuous band of flat sheet material, which may be pre-pleated longitudinally, is fed between a pair of endless forming assemblies which cooperate to form continuously a roughed-out shape of the final herringbone-pleated structure and which also advance to a bunching means positioned downstream from the forming assemblies. The bunching means operates to tighten up the folds of the roughed-out shape both longitudinally and transversely to provide the final structure.