Pre-operative central diabetes insipidus has been reported in 8-35% of patients affected with craniopharyngioma, and in 70-90% after surgery. The management of postoperative polyuria and polydipsia can be challenging and fluid balance needs to be closely monitored. The classical triphasic pattern of endogenous vasopressin secretion--an initial phase of symptomatic diabetes insipidus occurring 24 hours after surgery; a second phase of inappropriate vasopressin secretion potentially causing hyponatraemia; and a third phase with a return to diabetes insipidus occurring up to 2 weeks later--is often complicated by cerebral salt wasting and thirst disorders. Inadequate adrenal replacement therapy and anticonvulsant agent treatment may increase the risk of life-threatening hyponatraemia in the course of desmopressin (DDAVP) treatment. Appropriate management, in order to avoid life-threatening or disabling electrolyte disturbances, requires a good grasp of the relevant pathophysiology. We review here the pathophysiology and management of the multiple fluid disorders encountered following surgery for craniopharyngiomas.