Anaplastic thyroid cancer is a rare and rapidly deadly disease. In case of clinical suspicion (rapid growth, stony neck mass), diagnostic work-up should be carried out as a matter of urgency to enable prompt treatment. Multidisciplinary assessment involving the patient's referring specialists, the support care team, and if necessary, a geriatric oncology specialist should be performed and must take account of disease extent, comorbidities, general health status and the patient's wishes. Patients and their families should receive realistic information about the prognosis; either active treatment in parallel to support care or exclusive palliative care can be recommended from the outset. Despite the dismal prognosis, recent advances in tumor molecular profiling and treatment with the advent of targeted treatment and immunotherapy hold out great promise for the future. This article summarizes the consensus recommendations on management of anaplastic thyroid cancers by the ENDOCAN TUTHYREF network, a rare-cancer network of the French National Institute for Cancer (INCa).