Introduction and objective: Evaluation of lanadelumab efficacy in preventing angioedema attacks in patients with severe hereditary angioedema due to C1-inhibitor deficiency in Poland and descriptive analysis of this group of patients. Materials and methods: Retrospective analysis of patients treated with lanadelumab in Poland. Data were acquired from the electronic database of the National Health Fund, compiled from 15 hereditary angioedema centres. Only patients with severe hereditary angioedema course (at least 12 severe – abdominal, pharyngeal or laryngeal – hereditary angioedema attacks per six months, requiring on-demand medications) initiated treatment. The patients received lanadelumab 300 mg every two weeks. The efficacy of the therapy was assessed after six months. Results: Lanadelumab was initiated in a total of 43 patients (group B). Twenty of them achieved the follow-up point after six months (group A). The mean age of the patients was 44 years. The majority (76.7%) were female and 79% had a family history of hereditary angioedema. Most patients (95.3%) had HAE-1 (absolute deficiency of C1-inhibitor). On average, within six months before treatment, group A patients experienced 19.7 (95% confidence interval, CI: 16.06–23.33) severe hereditary angioedema attacks. In the six months following treatment initiation, the number of attacks decreased to an average of 0.5 (95% CI: 0–1.0), with significant reductions in all types of hereditary angioedema attacks – abdominal (p < 0.0001), pharyngeal (p < 0.005), and laryngeal (p < 0.05). Utilisation of on-demand medications dropped from an average of 23.5 (95% CI: 16.7–30.3) to 0.5 standard therapeutic dose (95% CI: 0–1.1). Conclusions: The study highlights the therapeutic potential of lanadelumab in managing hereditary angioedema, usually offering patients a complete resolution of severe hereditary angioedema attacks and release from dependence on rescue medication. Our results support the current paradigm shift in hereditary angioedema treatment.