An association between vasopressin and corticosteroids is proposed as a new palliative treatment of breast cancer. A first group of 88 patients with locoregional involvement or bone metastases gave 46 cases of remission (52.8%) with a mean time course of 17.4 months; a second group of 39 similar patients showed 23 cases of remission (58.9%). Worthy of note is the fact that the objective remissions in cases of locoregional involvement were respectively of 48.5% (mean time course of 18.5 months) and 52.1%. Meaning of the obtained results are discussed by comparison with corticotherapy alone data. The physiopathological bases of therapy are exposed which account for rather complicated directions for administration of the treatment.