Inasmuch as hereditary angioneurotic edema has generally been overlooked in the pediatric literature, it is hoped that this report may alert pediatricians to the possibiity of the existence of the disease in children of families with appropriate histories. It is likely that the symptomatology will not be severe in childhood; nonetheless, swellings and abdominal attacks do occur. Most important, the possibility that abdominal surgery will be helpful during bouts of abdominal pain due to hereditary angioneurotic edema should be considered unlikely. Markedly edematous viscera may provide technical difficulty during surgery, and undue physical trauma is not helpful. Hereditary angioneurotic edema differs from other non-allergic angioneurotic edema in that the tendency to attacks of edema is inherited as an autosomal dominant trait and swellings tend to be much more severe. The failure of anti-allergic medications and lack of evidence for allergy as a cause of attacks of hereditary angioneurotic edema tend to differentiate this disease from the more common allergic forms. Absence of serum inhibitor of C'lesterase further characterizes hereditary angioneurotic edema. Sera from persons with non-familial allergic and non-allergic angioneurotic edema have contained normal or greater than normal amounts of this inhibitor.7 In view of the definition of biochemical alterations in the blood of patients with hereditary angioneurotic edema and the possibility of identifying affected individuals before the onset of symptoms, it is to be hoped that a rational means for the prevention of symptoms can be devised.