We report on a healthy female with a unique relapsing transverse myelitis accompanied by herpes simplex virus type 1 (HSV-1) infection. Magnetic resonance imaging showed cord enlargement and increased signal intensity on T1-weighted image with gadolinium enhancement from T-4 to T-10 during the first attack and from C-1 to C-2 during the second episode. She was not diagnosed during the first attack. During the second episode, laboratory studies disclosed IgM and IgG antibodies to HSV at the outset with greater than fourfold increases in antibody levels in the serum and cerebrospinal fluid (CSF). Cells cultured from the CSF were positive for HSV-1 according to the immunofluorescence method. The presence of HVS-1 DNA in CSF was documented by polymerase chain reaction (PCR) technique. Acyclovir was given with a partial recovery. We anticipate that PCR assay of CSF will assist early diagnosis of herpetic central nervous system disorders.