Twelve male patients with absence of pubertal development and hypogonadotropic hypogonadism underwent a contrast-enhanced computed tomography of the sellar region and dynamic endocrine testing consisting of insulin-induced hypoglycemia, GnRH and TRH test. In two patients, clinically indistinguishable from the others, the presence of an empty sella turcica was demonstrated. They also showed, in comparison with patients with normal sellar morphology, an absent prolactin response to hypoglycemia with otherwise normal pituitary function. Empty sella, either due to congenital incompetence of the diaphragma sellae or to pituitary shrinkage due to regressive changes by hemorrhage, infarction and possibly autoimmune phenomena, may rarely be associated with hypogonadotropic hypogonadism.