Pre- and postoperative evaluation of hypothalamic-pituitary function was performed in six children, aged 5.5 to 13.3 years with craniopharyngiomas. Before surgery growth hormone deficiency (GHD) was documented in four, hypothalamic hypothyroidism in three, and secondary ACTH-deficiency and hyperprolactinaemia in one patient. Diabetes insipidus was absent in all patients. After neurosurgical treatment GHD was present in all, hypothyroidism in five, ACTH-deficiency in three, hyperprolactinaemia in three, and diabetes insipidus in four children. The study shows that all endocrine functions tested may be defective even before surgery, although diabetes insipidus seems to be a rare preoperative complaint. Surgical intervention, however, often leads to additional endocrine disorders. From the data presented here one may suggest that TRH stimulation tests, evaluation of serum prolactin, and lysin-vasopressin stimulation tests are the most useful investigations to distinguish between hypothalamic and primary pituitary disorders. © 1979 Springer-Verlag.