Varicella-zoster virus (VZV) is a cause of neurologic disease among humans. Both primary infection and recurrence may lead to neurologic infection and disease. Neurologic syndromes associated with acute VZV infection are caused by abnormal immune responses, the most frequent manifestation being cerebellar ataxia. Those associated with recurrences are often due to the direct effect of viral replication in the nervous tissue. VZV reaches the nervous system either through the bloodstream or by direct spread from sensory ganglia where it remains latent. Postherpetic neuralgia, acute encephalitis, aseptic meningitis and myelitis are the most frequent diseases and have been recorded both in association with herpes zoster and in the absence of a cutaneous rash. Early diagnosis may be established by detecting virus-specific DNA sequences in the cerebrospinal fluid (CSF) after amplification by the polymerase chain reaction and then confirmed by detection of intrathecally produced, specific IgG antibody. Virus isolation from CSF and antibody testing in serum are unsuitable for diagnosis. Early acyclovir therapy is recommended in immuno-compromised patients and those with serious disease.