This is a multinational, multicenter, prospective, observational cohort study of patients with HAE in the real-world setting. The study will include patients newly initiating garadacimab in routine clinical practice. Each participant will be followed for 48 months after index date (date of the first administration of garadacimab). Patient data will be collected from the HAE eDiary, patient medical records (MRs) and/or during a routine clinical visit and will be entered into the electronic case report form (eCRF) via an electronic data capture (EDC) system. Data pertaining to HAE attacks, prior HAE treatments, retrospective focused safety data collection, and healthcare resource utilization (HCRU) over a look-back period of 12 months prior to the enrollment will be extracted from the MR, and patients will also record retrospective HAE attack related data over a look-back period of 3 months prior to enrollment in the HAE eDiary. The primary aim of this study is to investigate the real-world effectiveness of garadacimab as measured by HAE attack rate before and after garadacimab initiation in patients with HAE over 24 months of follow-up. The study will aim to complement the data available from the clinical development program on the efficacy, safety, and health-related quality-of-life (HRQoL) in patients with HAE taking garadacimab.