To describe the occurrence of fatal laryngeal edema in patients with hereditary angioedema due to C1 esterase inhibitor deficiency. We describe 6 patients from various regions of Germany who died from laryngeal edema within the last 10 years. Furthermore, we conducted a retrospective survey of 58 patients with hereditary angioedema, originating from 46 affected families. The data were obtained from the attending physicians and from the patients' relatives. Among the 6 reported patients, aged 9 to 78 years, hereditary angioedema had been diagnosed in 3 and was undiagnosed in 3. None of them had an emergency cricothyrotomy or received C1 inhibitor concentrate. The interval between onset of the laryngeal edema and asphyxiation was 20 minutes in a 9-year-old boy, and in the other patients, the interval was 1 to 14 hours (mean for all, 7 hours). The retrospective survey of 58 patients with hereditary angioedema revealed 23 deaths by asphyxiation (40%). The average age of all 29 patients at the time of asphyxiation was 39 years. Laryngeal edema in hereditary angioedema may be fatal. Most of the patients asphyxiated between their 20th and 50th years of life, but asphyxiation can occur even in children. The possibility that the first episode of laryngeal edema may be fatal must be emphasized to the relatives, and attending physicians must have a high degree of awareness.