Abstract: A piston for a die-casting machine, in particular with a cold chamber, comprises a stem which extends from a proximal end to a distal end along a piston axis and a piston head which extends from the distal end of the stem and which has a side wall with at least one sealing area suitable to form a seal on the wall of said container of the press. A lubrication circuit suitable for favouring the sliding of the piston comprises first lubrication ducts made in the stem and ending at the distal end of said stem, and second ducts made in the piston head, fluidically communicating with said first ducts and coming out in the lateral wall at least in correspondence with said sealed area.