Targeted radionuclide therapy (TRT) plays an important role in management of oncology patients, particularly those with thyroid cancer, prostate cancer, or neuroendocrine tumor. Use of TRTs has expanded rapidly in recent years, with approval of new agents and indications. The number of ongoing TRT clinical trials suggests that this trend is likely to continue in the future. Adequate knowledge of potential adverse events and their management is essential for treating physicians to optimize outcomes in patients undergoing TRT. The authors review adverse events that may occur in TRT; their clinical manifestations, incidence, risk factors, and management; and strategies to prevent or decrease their risk of occurrence. ©RSNA, 2025.