We report the demonstration by magnetic resonance (MR) imaging of brain involvement in two of four subjects with human T-cell lymphotropic virus type I (HTLV-I) associated myelopathy. The four cases had slowly progressive spastic paraparesis, urinary incontinence, and positive HTLV-I antibodies in serum or CSF or both. Magnetic resonance revealed areas of abnormal intensity in the cerebral hemispheres of two of these cases; one of them also showed brain stem involvement. No spinal cord lesion could be detected in any case by MR.