In contrast to typical astrocytic tumors that show hypodense areas on computed tomographic images, some intracranial tumors show hyperdense areas on CT images. The major reasons for hyperdensity on CT images are hypercellular lesions, intratumoral calcification, and intratumoral hemorrhage. Malignant lymphomas, germinomas, and medulloblastomas show homogeneous hyperdensity on CT images because of their hypercellularity. Tumorous lesions such as subependymal giant cell astrocytomas, oligodendrogliomas, ependymomas, central neurocytomas, craniopharyngiomas, and meningiomas often present with hyperdense calcified lesions on CT images. Intratumoral hemorrhage also causes hyperdensity on CT images, and is often associated with metastatic brain tumors, glioblastomas, pituitary adenomas, and rarely with any of the other intracranial tumors. Although magnetic resonance imaging is now the major diagnostic tool for diseases of the central nervous system, the first imaging studies for patients with neurologic symptoms are still CT scans. Hyperdense areas on CT images are a clue to making an accurate diagnosis of intracranial neoplasms.