The main illness of the neural pituitary is diabetes insipidus (DI). MRI is essential if DI occurs during childhood, in order to highlight malignant germinoma prognosis of which remains excellent if the diagnosis is made as early as possible. In adults, primary intracranial tumours causing DI include craniopharyngioma, or pineal tumours. Infiltrative histiocytosis is another frequent aetiology. One third of previously considered idiopathic DI is in fact auto-immune. Early MRI findings advocate for such a diagnosis. Finally, meticulous analysis of the neural pituitary imaging may avoid several pitfalls and help the analysis of adenopituitary abnormalities.