Abstract: An instrument for the surgical removal of a conical piece of tissue having an aperture from a human or other animal body using a laser beam has a laser beam guide housing which is made up of a tube, through which the inlet laser beam passes, of an inlet deflecting member for deflecting the laser beam from its inlet direction and of an outlet deflecting member, arranged at a lateral distance from the latter, to deflect the beam along an outlet direction thereof so that on twisting the guide housing about the inlet direction the emerging laser beam sweeps out a conical surface. The outlet deflecting member is arranged on a boom member extending laterally from the tube. The instrument furthermore has a guide pin which centers the guide housing by being inserted in the tissue aperture. The guide pin and the guide housing are able to be rotated in relation to each other.