It is difficult to summarize an article of this type, in which the author is certain that his case has been presented fairly, but is aware that other views that are contrary could be stated and endorsed by pertinent clinical cases. Bearing this fact in mind, I wish to reiterate the following: Lateral canals are demonstrated in endodontic cases with much less frequency than they exist. This variance rarely, if ever, causes an endodontic failure. Some demonstrated lateral canals may really be other conditions. Preoperative evaluation should include examination of radiographs for lateral, as well as periapical, lesions. Lateral canals may be demonstrated by a variety of filling techniques. Careful canal preparation may enhance the frequency of such demonstration. Cases with necrotic pulps probably yield more frequent demonstration than do cases with vital pulps. Lateral canals harboring inflamed and/or infected material may cause pain during endodontic treatment. They may simulate periodontal disease and may cause problems with treatment if present when a tooth is left open for drainage. Periodontal disease may cause pulp exposure via lateral canals located coronally. Improper use of post room may lead to lateral failure from breakdown of tissue in a lateral canal. The enigma of the lateral canal has been the object of description and discussion in many articles, but no one is truly certain of their exact significance in endodontic therapy for the long haul.