This is a prospective, international, multi-center, non-randomized, single arm, open-label, postmarketing study to investigate the formation of inhibitory anti-C1-INH antibodies in HAE subjects treated intravenously with Berinert. Individual treatment duration per subject is 9 months, irrespective of the number of treated attacks. All subjects will receive 20 IU Berinert/kg body weight per attack.

Inclusion Criteria:

• Diagnosis of congenital C1-INH deficiency (HAE type I or II) and assessed by the investigator to likely require intravenous (IV) Berinert treatment during the study period.
• Male or female, ≥ 12 years of age at the time of signing informed consent.
• Written informed consent for study participation obtained before undergoing any study specific procedures.

Exclusion Criteria:

• Incurable malignancies in the last 6 months prior to study entry.
• Acquired angioedema due to C1-INH deficiency.
• All other types of angioedema not associated with C1-INH deficiency.
• Use of any C1-INH products other than Berinert within 30 days before the study, or planned use during the study.
• Immunization within 30 days prior to study entry.
• Autoimmune conditions requiring use of immunosuppressants during the study.
• Known or suspected hypersensitivity to C1-INH.
• Participation in any of the previous Berinert studies from which anti-C1-INH antibody results were submitted to the Food and Drug Administration.

Baseline to approximately 9 months.