Gangliogliomas are uncommon central nervous system (CNS) tumors composed of a mixture of glial and neuronal elements. Although these tumors can occur in any portion of the central nervous system, involvement of the ventricular system is rare. We herein report on two cases of gangliogliomas in the third ventricle in a 34-year-old woman and in a 52-year-old man. One patient presented only with headaches, and the other presented symptoms associated with panhypopituitarism and diabetes insipidus. In the first case the tumor in the middle portion of the third ventricle was successfully removed by a transcallosal subchoroidal approach. In the second case the hemorrhagic tumor was located in the anterior floor of the third ventricle and was removed by an anterior inter-hemispheric trans-lamina terminalis approach. To date, follow-ups of both patients have involved no adjuvant therapy, and there have been no signs of tumor recurrence on magnetic resonance images. The nature, radiological findings, and treatments of these tumors are discussed.