Abstract. In here, we describe a case of primary amenorrhea in the setting of chronic hydrocephalus caused by a posterior fossa
ependymoma. A 17-year-old female with primary amenorrhea presented to University-affiliated teaching hospital. Hormonal
studies were all normal. Cranial magnetic resonance imaging revealed chronic hydrocephalus with a 4 cm brain lesion that
was determined to be an ependymoma. After surgical resection, the patient had normal menstrual cycles. Primary amenorrhea
in association with hydrocephalus is usually due to hypothalamic hypogonadism. We report a case of an adolescent female
with normal gonadotropin levels and chronic hydrocephalus who presented with primary amenorrhea. Even in the presence of
normal hormonal studies and withdrawal bleeding after a progestational challenge, a head magnetic resonance imaging should
be performed in all females who do not have hypergonadotropic amenorrhea.