Perforations in the floor of the pulp chambers of molars offer an improved prognosis when treated aseptically and quickly. 2. Perforations in the apical third of the root canal, when made with a reamer or file that leaves 2 mm. or less of unfilled root canal space, have a good prognosis. 3. If a perforation, either mechanical or resorptive in etiology, occurs on the lingual surface and requires surgical management, prognosis is poor. 4. Recent advances in the use of calcium hydroxide to treat endodontic perforations show promise.