This invention relates to an apparatus for packing products in cartons; the apparatus includes a first feed line for feeding cartons, a second feed line for feeding products, a plurality of pushing elements, each of which includes a first carriage configured to run on a first rail defining an active path and a second carriage configured to run on a second rail defining an inactive path; a diverting unit is provided which is configured to divert the pushing elements in transit towards the active path or the inactive path and which includes a first diverting rail and a second diverting rail; also provided are detection means for detecting the presence of the carton and/or of the product and switching means for switching the diverting unit.