INTRODUCTION: We have previously argued that the clinical entity of dorsal third ventricular cyst in association with agenesis of the corpus callosum is a developmentally, radiologically, and clinically distinct and separate entity from the dorsal cyst of alobar holoprosencephaly. PATIENTS AND METHODS: Herein, we describe seven patients who underwent treatment of their dorsal third ventricular cyst with fluid diversion and shunting and report their long-term follow-up. The authors reviewed the literature and discrepancies identified in differentiating dorsal third ventricular cysts and holoprosencephaly. RESULTS: Postoperative scans showed evidence of cyst decompression and stabilization of head circumference. Two patients required shunt revision surgery for delayed malfunction while the remainder has had no revision surgery since initial placement. CONCLUSIONS: Given the good clinical outcome in comparison to alobar holoprosencephaly patients, we recommend fluid diversion in this population of patients.