Hereditary angioneurotic edema is a rare disease (250 cases currently identified in France). It is the most frequent among hereditary deficiencies of the complement system. This severe disease is fatal in 15-20% of the patients before 40 years of age. Death can be prevented if correct steps are taken in case of even minor trauma, which often trigger acute, potentially fatal, episodes. Danazol is used as preventive therapy before surgery and C1-esterase inhibitor or fresh frozen plasma is given for acute episodes. In case of obstetrical trauma, C1-esterase inhibitors should be used either as prophylaxy or as treatment. Fresh frozen plasma is used if C1-esterase inhibitors are not available. We report here our experience with three patients with known hereditary angioneurotic edema. Gynecology surgery was required in two.