Hereditary angioneurotic oedema is an autosomal dominant disorder associated with serum deficiency of functionally active C1 inhibitor protein (type 1) or normal serum level of functionally deficient C1-inhibitor (type 2). These biochemical abnormalities induce a complement activation which leads to episodic swelling of interstitial tissues usually of the abdominal viscera and of the upper airway with resultant asphyxia. Vasoactive peptides from the degradation of component C2 of the complement along with an activation of basophils by chemotactic substances from the degradation of C3 and C5 are the main mechanisms involved in vasodilatation and swelling. Attacks of angioneurotic oedema, sometimes fatal when involving the upper airway, can occur during any but usually during ear-throat-nose, dental or facial surgery. This article describes the pathophysiology and the main features of the disease in children. It reviews the different treatments used to avoid attacks or to cure an attack of angio-oedema once it has begun, both during planed surgery and during emergency surgery.