Hereditary angioedema (HAE) is a genetically determined disease characterized by recurrent episodes of subcutaneous or submucosal tissue oedema. Failure to respond to the classical treatment of angioedema with antihistamines, glucocorticosteroids as well as adrenaline is highly characteristic for HAE. Three main types of HAE have been described: type I – associated with hereditary reduction of C1 esterase inhibitor plasma concentration, type II – associated with its dysfunction and type III with both C1 inhibitor concentration and activity being within the normal range. We present a case report of a 16-year-old female patient with chronic spontaneous angioedema with normal activity and concentration of C1 inhibitor as well as an updated review of the current knowledge concerning pathophysiology, clinical picture, genetic background and possible treatment options for HAE type III.