Neuroimaging plays a crucial role in the diagnosis and therapeutic decision making in infectious diseases of the nervous system. MRI proved to be more sensitive than other neuroimaging modalities, including CT, in early diagnosing various types of CNS infectionsand their follow up. More recent magnetic resonance imaging techniques provide additional helpful information. However, the mainstay of diagnosis remains the detection of viral DNA or serological markers of specific infectious agents within the cerebrospinal fluid.