The invention relates to a vacuum system for securing items in printing machines, comprising a printing table (2) with a perforated surface and, in relation thereto, a vacuum system for securing the items to be printed, which comprises a box structure (8) connected to a suction system and provided with a perforated wall in relation to the surface of the printing table (2), said box structure (8) having lateral panels that vertically close the interior thereof, which panels can be moved in order to adjust the gap between them in relation to the width of the items to be printed.