Mediastinitis is a rare but life-threatening disorder. This infection, spreading from outside of the chest to the mediastinum, is most commonly derived from the pharynx or the teeth. In our patient, mediastinitis resulted from an eating disorder. She attempted to control her body weight by vomiting and damaged her pharynx by provoking vomiting. Eating disorder is exceptional as a cause of mediastinitis. This condition should be kept in mind in some common somatic symptoms and findings. An example of these is vomiting induced hypokalemia.