Separation of the periosteum from the rib edges, beneath the tenacious attachments of the intercostal muscles, as a step in the operation of subperiosteal rib resection, is notoriously tedious and time consuming. It is especially so in elderly or muscular subjects and in those whose pleuroperiosteum has been inflamed and thickened. At present, it is done with various types of periosteal elevators designed for general bone surgery; but none of them are satisfactory. The rapidly increasing number of thoracoplastic operations involving subperiosteal rib resection, especially for chronic empyema and pulmonary tuberculosis, has created a demand for an instrument that will strip the rib edges speedily, cleanly and without danger of wounding the pleura. I have designed such an instrument,<sup>1</sup>which has proved itself in practice. The instrument may be called a rib-edge periosteum stripper (<i>A</i>in the illustration). At the opposite end of the handle is the well known