Patients with the rare disease hereditary angioedema (HAE) suffer from recurrent acute attacks of edema. There is no curative therapy, but the frequency of attacks and quality of life of severely affected patients can be improved by prophylactic therapy. The monoclonal antibody lanadelumab has been approved for routine prophylaxis in patients with HAE since November 2018.In this prospective assessment, a long-term therapy with lanadelumab was initiated in 12 adult patients with HAE. We analyzed their course of disease 6 months after the start of long-term prophylactic therapy using a validated quality-of-life questionnaire and evaluated the frequency and severity of attacks as well as side effects. Furthermore, the therapy with lanadelumab was compared with the previous medication.To date, our study is the first prospective quality of life analysis in HAE patients under treatment with lanadelumab in real life conditions. Mean attack frequencies were reduced from 6.4 to 0.3 attacks per month and patient in our cohort (P<0.0001). No severe attacks occurred under lanadelumab prophylaxis. In all patients, quality of life increased significantly.Lanadelumab is an effective but expensive long-term prophylaxis for HAE patients. A favorable side-effect profile has been shown. J Drugs Dermatol. 2020;19(10):978-983. doi:10.36849/JDD.2020.5269.