After a brief survey on etiopathogenesis, clinic, paraclinic and differential diagnosis of the disease, the authors describe a patient, who at the age of 18 developed Anorexia nervosa, with a progressive body weight reduction from 70 to 30 kg. After the consultation with a psychiatrist the patient was admitted to a psychoneurological dispensary for treatment. Attention is drawn to the diagnostic difficulties and the internist was underlined, has to think and diagnose that, even though rare disease.