The chapter begins with a history of the discovery of anaphylaxis. Causes of anaphylaxis are discussed. Signs and symptoms of anaphylaxis in skin, respiratory, cardiovascular, gastrointestinal and neurologic systems are enumerated. Guidelines to arrive at a diagnosis of anaphylaxis are given by describing the differential diagnosis of anaphylaxis in a patient with hypotension, respiratory distress, postprandial collapse, and Flush syndrome. A precise, stepwise protocol is described for the management of anaphylactic shock.