A 24-year-old female was hospitalized for progressive headache and nausea. Computed tomography showed a mass lesion in the left lateral ventricle near the foramen of Monro. On light microscopy, this tumor morphologically resembled an oligodendroglioma. However, ultrastructural examination disclosed synapses and neuronal differentiation. Review of the literature revealed 21 cases of intraventricular neuronal tumors in adults that were diagnosed as central neurocytoma or differentiated neuroblastoma. Fourteen of the 21 patients were males and seven were females. Their ages ranged from 16 to 52 years and averaged 30.7 years. All of the tumors were located near the foramen of Monro and the clinical symptoms were primarily headache and nausea. The outcome was generally good. Surgical removal was the most effective treatment, whereas the effect of radiation therapy was unclear. The diagnosis requires demonstration of neuronal differentiation. Generally, the diagnosis is neurocytoma if the neuronal tissue is mature, with complete synapses, and neuroblastoma if it is immature. However, the criteria for differentiation between these two tumors are still controversial.