The paper reports our experience of a 15-year follow-up of 179 patients with hereditary angioedema (HAE). The disease is transmitted as an autosomal dominant trait and two variants have been described: type I characterized by functional and antigenic C1-inhibitor (C1-INH) deficiency and type II with normal or upper normal C1-INH antigenic levels but no functional activity. The clinical picture is characterized by self-limiting bouts of swelling in the subcutaneous and/or mucous tissues. Data about frequency, localization and possible triggering factors of HAE attacks are reported. Analysis of genomic DNA from our patients using a C1-INH cDNA probe demonstrated the presence of restriction fragment length polymorphisms tightly linked with the disease in a minority of them. Data concerning prophylaxis and treatment of HAE attacks are also shown.