We report the pathological and molecular biological findings of human T-cell lymphotropic virus type 1 (HTLV-1) infection of the spinal cord in a patient with a chronic progressive myelopathy. Light microscopy disclosed loss of myelin and axons, thickening of blood vessels and a lymphocytic cell infiltrate in the spinal cord especially at the cervical and thoracic levels. Electron microscopy confirmed the vascuolar appearance seen with light microscopy but virus particles were not observed. The HTLV-1 gag gene could be amplified (by polymerase chain reaction) from cervical spinal cord tissue while not from elsewhere in the neuroaxis. The presence of HTLV-1 geonomic material in spinal cord tissue has not been previously reported.