OBJECTIVE: To review the etiologic factors, pathophysiology and specially the therapeutic management of the anaphylactic reactions.METHODS: The bibliographic review included textbooks of allergy and intensive care and Medline references.RESULTS: Anaphylactic reactions that result from the rapid release of potent pharmacologically active mediators from mast cells or peripheral blood basophils may involve several organ systems with some risk of death.COMMENTS: Anaphylaxis is a clinical syndrome with significant mortality rate. There are several etiologic factors that trigger the process and multiple pathophysiologic mechanisms involved. Early diagnosis and an effective therapy lead to a better prognosis. In the majority of the cases prophylactic measures are needed to avoid other episodes.