Metastases to the pituitary gland are uncommon causes of hypopituitarism, to be particularly considered in patients affected with disseminated cancers, arising in the breast or in the lung. Differential diagnosis could be correctly addressed by the concomitant presence of diabetes insipidus, due to the prominent involvement of the posterior lobe, and by some neuroradiological findings. We report the case of a 58-year-old woman, suffering from advanced breast cancer, who developed diabetes insipidus and anterior hypopituitarism. Magnetic resonance images showed diffuse encephalic metastatic lesions, with a thickened pituitary stalk, loss of high signal intensity of posterior lobe and a mildly enlarged and inhomogeneously enhanced adenohypophysis. Substitutive hormonal therapy was started, but the patient died five months later due to the progression of the neoplastic disease.