We reviewed the experience at the Mayo Clinic with neurologic complications related to herpes zoster in patients with systemic cancer. Aside from pain, the most common neurologic complication was zoster-associated meningoencephalitis, which occurred in 9 of 1,125 patients. In these nine patients, the most common underlying malignant lesions were chronic lymphocytic leukemia and lymphoma. All patients in whom meningoencephalitis developed had trigeminal zoster or disseminated zoster. The primary neurologic symptoms were headache, confusion, and somnolence. Nuchal rigidity and fever were uncommon. The response to treatment with acyclovir was generally favorable.