In order to evaluate the secretory patterns of luteinizing and follicle-stimulating hormones in various forms of abnormal sexual development, plasma levels of these hormones were measured every 20-30 minutes during sleep in 9 patients with true precocious puberty and 2 patients with primary hypogonadism. Seven patients with idiopathic precocious puberty and 2 patients with organic CNS lesion-related precocious puberty exhibited fluctuating plasma concentrations of these hormones that resembled findings in normal pubertal subjects who had significantly increased concentrations of plasma luteinizing hormone during sleep. Two patients with primary hypogonadism also showed episodic fluctuation of both hormones and augmented luteinizing hormone concentrations during sleep. These results suggest that the pubertal sleep-related gonadotropin secretion is dependent on the sleep-entrained CNS mechanism, and that the central nervous system plays an important role in sexual maturation.