A case of a large, symptomatic, supracallosal interhemispheric arachnoid cyst is presented. Positive contrast-enhanced computed tomographic (CT) cystography after stereotactic puncture and aspiration demonstrated lack of communication between the cyst and the subarachnoid space or ventricular system. A cystoperitoneal shunt was successful in relieving the patient's symptoms for 5 years. A delayed shunt infection after gynecologic surgery necessitated removal of the shunt, and was complicated by asymptomatic intracystic hemorrhage. Thereafter, serial CT and magnetic resonance imaging scans showed eventual disappearance of the cyst.