Anaplastic thyroid carcinoma is an undifferentiated tumour and lethal. Conventional treatment has not demonstrated clear therapeutic efficacy in prolonging the survival in metastatic anaplastic thyroid carcinoma. We report a case of a 44-year-old woman who was diagnosed with stage IV anaplastic thyroid carcinoma with positive anaplastic lymphoma kinase-echinoderm microtubule-associated protein-like-4 mutation. She demonstrated a good response to anaplastic lymphoma kinase inhibitors therapy with stable disease status for more than six months. This case report shows clinical efficacy of anaplastic lymphoma kinase inhibitor in a patient with stage IVC anaplastic thyroid carcinoma with positive anaplastic lymphoma kinase mutation.