Four cases of precocious puberty secondary to intracranial tumors are reported. A 3 year and 11 month old boy had a teratoma in the left lateral ventricle and total surgical excision was followed by recovery. An 8 year old girl with a protoplasmic astrocytoma of the third ventricle diagnosed by biopsy, followed by shunting and cobalt therapy was discharged improved. A five year old boy with an extensive astroblastoma of the diencephalon died following biopsy and shunting of cerebrospinal fluid. A posterior hypothalamic hamartoma totally excised from a 3 year old girl was followed by remission of the precocious puberty. The theories of hormonal mechanisms leading to precocious puberty are presented. It is stressed the importance of pneumoencephalography in the diagnosis of intracranial hamartomas, for they lack neurological signs.