Chronic progressive myelopathy (CPM) is a difficult clinical problem. Many patients who present with CPM turn out to have a spinal form of multiple sclerosis (MS), but until there is clear lesion dissemination, a definite clinical diagnosis cannot be made. We have looked for MS-related abnormalities in 72 patients with CPM. The mean age of onset was 42 years, mean duration was ten years, and mean Kurtzke disability rating was 4.5. Studies performed were cerebrospinal fluid electrophoresis for oligoclonal banding, pattern-reversal visual evoked responses, blink reflex latencies, and computerized axial tomography. Oligoclonal banding was found in 32 patients (44%), patterned visual evoked responses were abnormal in 32 (44%), and blink latencies were abnormal in 40 (56%). A least one of these studies was abnormal in 61 patients (85%) and at least two in 48 (66%). The CT scan was abnormal in 38 )53%), 36 with atrophy and 3 with low-density or enhancing lesions. These results suggest that at least 44% of patients with CPM may have MS that could be diagnosed by oligoclonal bands. Other physiological tests suggesting diffuse or disseminated disease bring the total to 85%. Only autopsy follow-up will tell us the exact diagnostic accuracy of these studies in this complex syndrome.