MR imaging now appears as the best tool for diagnosis and pre-therapeutic assessment of tumors arising in the third ventricle (V3), as MR images can be obtained in the axial, coronal, and sagittal planes. MRI makes certain the location of the tumor in the V3 and delineates the anatomical landmarks in order to plan the surgical approach. It also allows the evaluation of associated hydrocephalus. Colloid cysts, choroid plexus papillomas, cavernomas, subependymal giant cell astrocytomas and germ-cell tumors may exhibit specific radiological features.