Isolated central nervous system vasculitis (ICNSV) is a vasculitis limited to the central nervous system. Its etiology and pathogenesis has not been exactly elucidated yet. It is predominantly seen in the fourth to sixth decades. Neurological symptoms in ICNSV can manifest in a broad spectrum, ranging from headache to stroke. A high degree of clinical suspicion is of great importance for diagnosis. Although there is no definitive diagnostic laboratory / serological test for ICNSV; laboratory tests are performed in patients with ICNSV to exclude secondary causes. CSF analysis usually demonstrates a high protein content and lymphocytic pleocytosis. Imaging findings are quite variable, ranging from small ischemic changes to large areas of infarction, hemorrhage, white matter edema also contrast enhancement. Magnetic resonance imaging is the most commonly used imaging modality in the workup of patients with suspected ICNSV. Vessel wall imaging MR technique, which has been used frequently in recent years, can be helpful in the diagnosis of ICNSV, determination of the appropriate biopsy location and follow-up after treatment. Cerebral digital subtraction angiography is considered the most sensitive imaging modality for the diagnosis of ICNSV; but the findings are not pathognomonic. Histological confirmation obtained with cerebral and meningeal biopsy samples is the gold standard for the definitive diagnosis of ICNSV. In this chapter, we discuss the ICNSV in detail with a diagnostic algorithm in the light of modalities that can be used in diagnosis