Thyroid storm is a rare, life-threatening condition that can be caused by various pathologies including serious conditions associated with human chorionic gonadotropin (hCG)-producing tumours. We present the case of a 17-year-old male patient with a 1-month history of dyspnoea and a 3-day history of palpitations and fever. General examination revealed a left testicular mass. Blood tests revealed β-hCG >225,000 mIU/ml, thyroid-stimulating hormone (TSH) 0.02 IU/ml, and thyroxine (T4) 19.07 μg/dl. He was admitted with thyroid storm. Treatment with antithyroid drugs and chemotherapy was started, but the patient died on the third day of admission. This case highlights a rare occurrence of thyroid storm linked to testicular choriocarcinoma, and provides a necessary reminder that, in some instances, hCG at very high levels can exert a thyrotropic effect due to its molecular structure, which is similar to that of TSH. CONCLUSIONS Thyroid storm is rarely associated with testicular choriocarcinoma.Sometimes, human chorionic gonadotropin at very high levels can exert a thyrotropic effect due to its molecular structure, which is similar to that of thyroid-stimulating hormone.The clinical course and management of thyroid storm secondary to testicular choriocarcinoma in a young male is described.