BACKGROUND There are two types of amiodarone-induced thyrotoxicosis (AIT). Type 1 AIT is increased synthesis of thyroid hormone, whereas type 2 AIT is excess release of thyroid hormone due to a destructive thyroiditis. However, cases leading to amiodarone-induced thyroid storm are rare. METHODS A 75-year-old man with a history of chronic heart failure, nonsustained ventricular tachycardia, and atrial fibrillation was treated with amiodarone from age 72. He was presented to the emergency department with edema of the legs and dyspnea on exertion for 3 weeks. He was diagnosed with thyroid storm associated with type 2 AIT on the basis of no pre-existing thyroid disease and long-term amiodarone administration without appropriate medical attention and thyroid function tests. CONCLUSIONS This case report suggests that amiodarone can cause not only AIT but also thyroid storm. Regular medical appointment and thyroid function tests can avoid this critical illness.