A reuse method for utilising reject rolls being produced in paper and cardboard factories, wherein from the reject rolls (1) there are made straight roll cores (8) having the same size in their inner and external diameter and varying in length, the straight roll cores being defined by the width of each reject roll (2); the straight roll cores are joined end-to-end to form a long, continuous core tube (12), and the core tube is cut to size to form roll cores (14) of paper and cardboard industry.