Neurological complications caused by varicella-zoster virus (VZV) were diagnosed in 13 human immunodeficiency virus (HIV)-infected patients in our hospital. There was a favorable influence of highly active antiretroviral therapy (HAART) in the prevalence of these disorders among acquired immunodeficiency syndrome (AIDS) patients: Since 1996, only 1 of 961 AIDS patients had VZV neurological disease, compared to 9 of 1088 patients before that year (P =.02). Polymerase chain reaction (PCR) detected VZV DNA in cerebrospinal from 4 of 5 patients with VZV neurological disease, and from 2 of 130 HIV-infected patients with other neurological diseases (sensitivity 0.8, specificity 0.98 [95% confidence intervals 0.45-1 and 0.96-1, respectively], positive predictive value 0.94).