We documented hypothalamic-pituitary dysfunction in three patients with congenital herniation of the brain through the base of the skull (basal encephalocele). All had growth hormone deficiency, although one has attained normal height. One had diabetes insipidus. Two had hypogonadotropic hypogonadism. Prolactin secretion was elevated in one, normal in another, and borderline low in the third. Two patients were euthyroid, but in response to thyrotropin-releasing hormone (TRH) injection, one patient's thyrotropin (TSH) level increased to levels exceeding normal while the other's did not attain normal levels. In the third patient, TSH response to TRH went from subnormal to normal after treatment with growth hormone and thyroxine. No patient had evidence of ACTH deficiency. These heterogeneous findings do not permit assignment of an unequivocal anatomic or functional site to the endocrine defect (s). Pituitary function should be evaluated in all patients with basal encephalocele, and this entity should be considered in the differential diagnosis of central endocrine malfunction.