Inclusion Criteria:  Participant is aged >= 12 years at the time of the last documented HAE attack in the eligibility period. Participant has a physician-confirmed diagnosis (or confirmation in medical records) of HAE type I or type II. Participant had initiated LTP with lanadelumab during the eligibility period. Participant provides informed consent or assent prior to the initiation of any study procedures (where required by local regulations).  Exclusion Criteria:  Participant was enrolled in a therapeutic investigational drug or device trial during the observation period. Participant without documented HAE attacks in the pre-index period and/or without available participant diary or systematic documentation of HAE attacks in the medical records during the post index period.