ABSTRACT Cherubism is a rare autosomal dominant disease characterized by expansile osteolytic jawbone lesions. The effect and safety of off-label calcitonin treatment during the progressive phase of the disease are not well described. In this retrospective study, we present data on the radiological response and adverse effects of subcutaneously administered calcitonin in a cohort of nine cherubism children (three female, six male). Two of the nine patients underwent two separate treatment courses with a significant off-treatment interval in between; therefore, a total of 11 treatment courses with a mean duration of 17.9 months (range <1 to 35, SD 10.8) were studied. To measure the response, the cumulative volume of cherubism lesions was calculated from available three-dimensional imaging. The primary outcome was the change in the volume of lesions during calcitonin treatment and only assessed for the eight treatment courses with a minimal duration of 6 months. A statistically significant reduction in the mean cumulative volume of lesions was seen regardless of treatment duration. Average volume reduction was highest in the first half year of treatment, with a gradual, ongoing reduction thereafter. For the secondary outcome, the change in the cumulative volume of lesions after treatment cessation was assessed for the seven treatment courses with follow-up imaging available. After six of these seven treatment courses, the cumulative volume increased again but remained undoubtedly smaller than the initial volume at the start of therapy. Adverse effects were assessed for all 11 treatment courses and occurred in 73% of them. Most adverse effects were mild and low grade, with the most severe being one grade 3 symptomatic hypocalcemia requiring hospitalization and early treatment termination. Calcitonin treatment seems effective and tolerable in treating actively progressing cherubism in children. However, further research is required to better understand the pharmacological treatment of cherubism, including also other drugs, dosing, and protocols. © 2023 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).