Introduction: We report a very rare case of paraneoplastic chorea due to lung cancer that was ameliorated by administering tetrabenazine, the only agent used for treating the chorea of Huntington disease. Case: A 92-year-old woman was diagnosed with lung cancer but only followed up, based on advanced age and her own wishes. Given the absence of treatments such as chemotherapy, the lung cancer was not histologically diagnosed. During follow-up, involuntary movements appeared and paraneoplastic chorea was diagnosed. Therefore, she could not live alone and was admitted to a nursing home. Triple combination therapy with valproic acid, tiapride hydrochloride and risperidone was started, and showed efficacy for her symptoms. The symptoms showed amelioration but persisted in the upper extremities, face and neck. A neurologist suggested to her family that tetrabenazine, the only medication used for Huntington’s chorea, might be effective. After admission to our hospital, her family requested tetrabenazine. As both she and her family were suffering mental distress because “she was trapped in a body that moved regardless of her will”, we initiated tetrabenazine at a dose of 12.5 mg/day. After starting tetrabenazine, chorea of the upper extremities, face and neck almost disappeared. Moreover, her speech became clear and she spoke normally with her family. Discussion: Tetrabenazine is a drug receiving insurance reimbursement only for Huntington’s chorea, but was effective in this case. In our view, this treatment palliated the patient’s physical distress and the mental distress that she and her family were experiencing due to her paraneoplastic chorea.