Hereditary angioedema (HAE) is an autosomal dominant disorder characterized by recurrent edema of the oropharynx, the extremities, and by abdominal pain. This disorder is caused by a defect in the C1 esterase inhibitor (C1 INH) which inhibits the first component of complement (C1). Four generations of a family are described and laboratory data of five individuals of this family are given as these individuals presented for general otolaryngologic procedures. The mortality of acute laryngeal edema is described to vary from 6% to 54% and may necessitate a tracheotomy as a life saving measure A deficiency of IgA is also noted in this family, and to our knowledge, this is the first time this has been shown in association with HAE. Present therapy consists of long utilization of danazol, an attenuated androgen. Recently a partially purified C1 INH has been reported for acute episodes of HAE, and preliminary results are promising.