Hereditary angioedema (HAE) is a rare autosomal dominant disorder caused by a C1-inhibitor deficiency. It is characterized by potentially life-threatening recurrent episodes of angioedema of the skin and mucosa. Several recent studies have further elucidated the immunology of HAE implicating bradykinin, the key mediator of the contact system. This article reviews the pathophysiology, subtypes, and clinical features of HAE. Therapeutic approaches for various clinical situations (emergency and prophylactic regimens) are also discussed.