PURPOSE: Intraventricular neurocytoma, a recently recognized benign primary cerebral tumor of young adults, can be confused with oligodendroglioma and other neoplasms. The purpose of this paper is to describe the characteristic CT and MR imaging findings of intraventricular neurocytoma. MATERIALS AND METHODS: CT and MR imaging findings of five patients (M:F=2:3, ages 17-64, mean age 41) with intraventricular neurocytoma were retrospectively reviewed. All patients underwent CT scan and cerebral angiography. In four patients, MR imaging was performed and axial, sagittal, and coronal T1- and T2-weighted spin echo and gadolinium enhanced images were obtained. We evaluated the tumors with regard to location, size, shape, CT density, MR intensity, enhancement pattern, and internal texture such as calcification and cystic changes. RESULTS: All tumors were located in the lateral ventricles; especially around the foramen of monro (four cases). Their size varied from 1.0 x 1.5 cm to 4.0 x 3.0 cm and all showed a lobulated appearance. On precontrast CT scan, all tumors showed heterogeneous density due to multiple intratumoral calcifications and cystic changes. MR imaging showed a heterogeneous signal with iso- or slight hyperintensity on T1-weighted and hyperintensity on T2-weighted image, relative to cerebral parenchyme. After contrast injection, varying degrees of enhancement were noted on both CT and MR images. CONCLUSION: An intraventricular mass with or without calcification and cystic changes in the anterior portion of the lateral ventricle is suggestive of intraventricular neurocytoma. MR imaging is better in defining the exact location and cystic changes of the tumor, whereas CT is better for the characterization of calcifications.