The authors evaluated the efficacy of short-term danazol prophylaxis in 12 hereditary angioedema patients undergoing maxillofacial or dental procedures. Hereditary angioedema is an autosomal dominant disorder resulting from the deficiency of the C1 esterase inhibitor. Characteristic clinical manifestations include the formation of subcutaneous and submucosal edema. The latter can lead to fatal upper airway obstruction. Edematous attacks can be precipitated by tissue injury from operative procedures, dental surgery in particular. In patients undergoing surgical and diagnostic procedures performed in the cephalic and cervical regions, such attacks can be prevented by appropriate drug therapy. Short-term danazol prophylaxis was effective in all 12 patients with a history of edematous complications that had occurred after dental procedures; none of them developed postoperative edema. The serum levels of complement components determined pre- and postoperatively as well as at 6- and 12-hour intervals also demonstrated the efficacy of prophylactic therapy.