Congenital hypopituitarism. Report of 23 cases Background: Congenital hypopituitarism is an uncommon cause of hypophyseal insufficiency. It is less common than growth hormone deficiency, which has an incidence of 1:4.000 to 1:8.000 live newborns. Early diagnosis of this condition is important to prevent impairment of cognitive function, poor growth and alterations in metabolic profile in these patients. Aim: To report 23 patients diagnosed with congenital hypopituitarism. Material and methods: Retrospective review of clinical records of 23 patients (12 males) with congenital hypopituitarism, diagnosed during a 21 years period. In a group of 16 patients a molecular study was performed searching for mutations in HESX1, PROP-1 or POUF-1. Results: Short stature was the most frequent sign at the first evaluation, followed by neonatal hypoglycemia and presence of nistagmus, strabismus, atrophic optic nerve or malformations in the middle line showed in CNS imaging, suggesting septo-optic-dysplasia. All male patients diagnosed during neonatal period, exhibited micropenis. CNS images showed isolated hypophyseal hypoplasia or associated to an ectopic neurohypophysis in most patients. No patient in the subgroup subjected to molecular analysis had any of the mutations in the searched genes. Conclusions: The diagnosis of hypopituitarism must be based on clinical grounds, specially when hypoglycemia, prolonged jaundice, micropenis or midline alterations are found in the neonatal period (