We used the polymerase chain reaction (PCR) to demonstrate cytomegalovirus (CMV) DNA in the CSF of a patient with the CMV radiculomyelopathy syndrome. To investigate the significance of this finding, we also performed PCR for CMV on CSF samples from 30 patients with human immunodeficiency virus (HIV) infection and neurologic disease, four patients with solid organ transplants including three with active CMV infection, and 10 patients with no clinical suspicion of HIV or CMV infection. There was CMV DNA only in patients with HIV, and it was present more often in patients with evidence of spinal cord dysfunction. Our results suggest that PCR may be useful in the rapid diagnosis of CMV infection of the CNS in patients with HIV and that the radiculomyelopathy syndrome may represent only part of a spectrum of CMV-induced spinal cord dysfunction in these patients.