14 cases of hypopituitarism associated with mid-line defects are reported: 7 with septo-optic dysplasia, 5 with agenesis of corpus callosum and septum pellucidum without optical lesion (2 with cleft palate), 1 with familial pituitary aplasia and 1 with mediofrontal cutaneous aplasia. The most striking features in these patients are: precocious signs of pituitary deficiency, mainly hypoglycemia; micropenis and cryptorchidism in males; decrease of growth velocity 2 months to 6 years after birth. Neuroradiological investigations, evaluation of somatotropic and corticotropic secretions with glucagon test, and evaluation of thyrotropin and prolactin secretion with thyroliberin test, offer in the youngest patients the best way to precocious diagnosis and treatment.