The instrument consists of two or more straight tubes (13,15) slidable one inside another, a straight rod (10) of smaller diameter than the smallest tube, and a cutter (14) which fits inside the largest of the tubes and has a cutting tip on one end and a handle (22) on the other. The cutting tip is in the shape of a toothed ring (21) which can cut away and remove an intervertebral disc or a portion of it. Each tube is recessed for a length of at least 2 mm at the end designed to make contact with the disc, the sides of the recesses forming an angle of 20 degrees relative to the generating line of the tube. The other ends of the tubes have annular grooves (18) at regular intervals to act as insertion depth indicators. The diameters of the different tubes vary from 2 to 6 mm.