The presentation of anorexia nervosa or bulimia nervosa to the dentist as a result of referral from a psychiatrist, psychologist, or eating disorders clinic will circumvent the diagnostic problems associated with the condition. Under these circumstances, the dentist may assume a willingness, or at least a resignation, on the part of the patient about acknowledging the condition and the implications for the dentition. Dentists are increasingly aware, however, that patients may come to them for dental care because of pain related to excessive tooth erosion due to vomiting. Rather than acknowledge the cause, the bulimic patients may be inclined to obfuscate the history by means of elaborate excuses. Thus, confronted with a patient who is determined to thwart the objectives of taking a clinical history, the dentist must rely on signs and symptoms as the key to the diagnosis of anorexia or bulimia nervosa. There is no one diagnostic feature of the head or mouth that is pathognomonic for anorexia or bulimia nervosa but rather an array of evidence, which, taken in aggregate, may help the dentist to reach the probable diagnosis. Hopefully, the dentist can begin the task of encouraging the patient to seek additional help.