The present invention relates to a system and method for rolling a seamless tube. The plant comprises a main rolling mill with adjustable rolls for mandrel-rolling a semi-finished tube. The plant also comprises a fixed-roll extracting/reducing mill positioned downstream of the main rolling mill. The extracting/reducing mill is designed to extract the semi-finished tube from the mandrel and reduce its diameter to a predetermined value close to that desired for the finished tube. Finally, the plant comprises a adjustable-roll sizing mill. The sizing mill is positioned downstream of the extracting/reducing mill. This sizing mill is designed to adjust the radial position of the rolls and define the diameter of the outgoing tube.