This report describes a woman who experienced a high number of laryngeal hereditary angioedema (HAE) attacks during her participation in the IMPACT2 clinical trial of C1-INH concentrate. A 53-year-old caucasian female with a 31-year history of type 1 HAE experienced 16 laryngeal HAE attacks between 3 August 2006 and 23 February 2010, 15 of which were severe. All laryngeal attacks were successfully treated with C1-INH 20 U/kg, with a median onset of relief of 14 min and median time to complete resolution of symptoms of 20 h, and no need for redosing. The reliable success of C1-INH for these potentially fatal events is reassuring for both patients and prescribers.