Approximately 9 to 15% arachnoid cysts occur in the sellar or suprasellar region. The optimal management of symptomatic suprasellar cysts continues to pose a challenge to neurosurgeons. This case report describes a patient with a suprasellar arachnoid cyst who presented at the age of 3 and was followed for 20 years after cystoventriculostomy. A girl was referred to neurosurgery department by a pediatric clinic because computed tomography demonstrated a suprasellar cystic lesion. The neurological examination and all routine blood tests including hormone profiles were normal. The physical examination was unremarkable except premature thelarche. Stereotactic ventriculocystostomy was performed using a catheter providing permanent internal drainage. Postoperative cystoventriculography showed contrast medium in both the cyst and the ventricles. Control computed tomography confirmed that the ventricular cyst catheter was within the cyst. During a follow-up of 20 years, signs of precocious puberty disappeared and the girl showed normal sexual development. Endocrine profiles and visual function remained normal. The stereotactic approach to suprasellar arachnoid cysts is a safe procedure in experienced hands.