Liu KX, Lamba N, Marcus KJ, et al. - Since nonmalignant vascular anomalies (VA) comprise a heterogeneous spectrum of conditions characterized by aberrant growth or development of blood and/or lymphatic vessels and can cause significant morbidity, researchers desired to know about long-term outcomes after radiotherapy in pediatric and young adult patients with nonmalignant vascular anomalies (VA). Thirty patients who were diagnosed with nonmalignant VA and treated with radiotherapy prior to 2017 and before the age of 30 have been identified. The most common reason for the first radiotherapy was progression despite standard therapy and/or urgent palliation for symptoms (57%). Telangiectasias, fibrosis, xerophthalmia, radiation pneumonitis, ovarian failure, and central hypothyroidism were among the long‐term complications. A small group of pediatric and young adult patients with nonmalignant, high‐risk VA received a clinical benefit from radiotherapy with expected toxicity, however, the majority progressed. Prospective studies are required to identify indications for radiotherapy in VA refractory to medical therapy, including targeted inhibitors.