The case of a 55-year-old woman with postpartum (at age of 22) hypopituitarism is reported. The patient, with signs of myxedema, was admitted to a psychiatric hospital for hallucinations. In addition to routine tests and measurements of thyroid hormones level, magnetic resonance imaging (MRI) of the brain and pituitary region was performed. The results of MRI showed cerebral atrophy and a large "empty sella". On the basis of clinical, laboratory and instrumental data, a diagnosis of panhypopituitarism with prevalent hypothyroidism was achieved. Many hypotheses could be made regarding its pathogenesis. Initially we considered the diagnosis of Sheehan's syndrome in which the sella turcica usually presents normal or reduced dimensions. However the presence of a large "empty sella" with thin walls, excludes this diagnosis. The delay of menarche and the short stature suggest the hypothesis of a preexistent pathological condition. It is possible that the patient had liquefied pituitary adenoma as a consequence of the postpartum shock or that she was hypothyroid, a condition in which the "empty sella" is very common.