Hereditary angioedema resulting from the deficiency of the C1 inhibitor (HAE-C1-INH) is a rare, but potentially life-threatening disorder characterized by paroxysmal episodes of subcutaneous or submucosal edema. Early diagnosis is essential. Management is aimed at the prompt elimination of full-fledged attacks, as well as at the prevention of edematous episodes. The most straightforward means for therapy is supplementation with the deficient C1-INH protein. Placebo-controlled and open clinical studies have established that nanofiltered, human C1-INH concentrate, Cinryze® (ViroPharma Inc., Exton, PA, USA) (C1-INHCi), administered in 1,000 U doses is an effective and safe remedy for edematous episodes of HAE-C1-INH, regardless of the localization of the attack. Clinical manifestations rapidly improve and then resolve completely following treatment with this medicinal product. Additionally, C1-INHCi is also appropriate for pre-procedural or for routine prophylaxis. The administration of 1,000 U C1-INHCi before the (dental, surgical, or interventional diagnostic) procedure reduced the incidence of edematous episodes compared with placebo, and this reduction proved significant during routine prophylaxis with the administration of this dose every 3-4 days. Relapses did not occur, and repeated dosing had no influence on the efficacy of the preparation. Patients also tolerated treatment with C1-INHCi well. The safety of this preparation was confirmed by the absence of viral transmission as well as by the lack of antibody formation against C1-INH during treatment. Nowadays, C1-INHCi for intravenous use is the only medicinal product indicated both for the prevention and management of edematous attacks.