Immune checkpoint inhibitors (ICIs) are new cancer therapies that function either by blocking the interaction between programmed cell death 1 (PD-1) and programmed cell death ligand 1 (PD-L1) or by inhibiting cytotoxic T-lymphocyte antigen 4 (CTLA-4). The utilization of ICIs has improved outcomes for advanced, relapsed, or refractory malignancies in adults and children. Concerns have been raised due to immune-related adverse events (irAEs). The most frequently observed endocrine irAEs in children and adolescents include adrenal insufficiency, diabetes, thyroid dysfunction, and hypophysitis. The Clinical Practice Committee of the European Society for Pediatric Endocrinology (ESPE) aims to highlight the current knowledge and gaps on ICI irAE on the endocrine system in children and adolescents.