Anaphylaxis is an acute systemic reaction caused by IgE-mediated immunological release of mediators from mast cells and basophils to allergenic triggers, such as food, insect venoms, and medications. An alternative definition was recently proposed as follows: anaphylaxis is a "condition caused by an IgE mediated reaction" that is "often life threatening and almost always unanticipated." The reaction can be severe enough to lead to the rapid onset of symptoms, including dizziness, upper airway occlusion, bronchial constriction, hypotension, urticaria, cardiovascular arrhythmias and possible cardiac arrest. The incidence or prevalence of anaphylaxis in Korean pediatrics has not known. Thus, Epidemiology of Anaphylaxis in Pediatrics based on the data from Korean Health Insurance Review and Assessment Service (KHIRA) from 2001 to 2007 and questionnaire to the member of Korean Academy of Pediatric Allergy and Respiratory Disease (KAPARD) who are working at the training hospitals was studied. The incidence of anaphylaxis under age 19 is 0.7-1.0 per 100,000 year-person. The causes of anaphylaxis based on data from KHIRA were unknown (61.7%), food (24.9%), medications (12.4%), and serum (1.0%).