Multiple Sclerosis (MS) cases found at autopsy in patients who had died from other diseases and in whom no sign or symptom could be related to MS are called "asymptomatic". Three cases are reported. The first patient was a 62 year old man who presented with a slowly progressive disturbance of gait, incontinence and deterioration of intellectual function. A falx meningioma was surgically removed. The patient died 3 years later with an acute respiratory illness. Examination of the brain disclosed evidence of the operation and numerous old plaques disseminated through the cerebral hemispheres (centrum semi-ovale, periventricular regions, internal thalamus and junction between cortex and white matter) and in the brain stem. The second case, a 77 year old woman with diabetes mellitus and hypertension, presented with cortical blindness and disturbances of memory of acute onset. She died one year later. Examination of the brain showed multiple infarcts involving the territories of both posterior cerebral arteries and the left middle cerebral artery. Numerous old plaques were seen in the periventricular regions, in the corpus callosum and in the left middle cerebellar peduncle. The third case, a 60 year old woman with mitral and aortic stenosis, presented with cortical deafness and transient right hemiparesis. She died 5 years later. Brain examination showed infarcts involving both middle cerebral artery territories. There was also many old plaques in the periventricular areas, thalamus, internal capsule, centrum semi-ovale, brain stem and right nucleus dentatus. In the 3 cases, the optic tracts were normal. The spinal cord, examined only in the first case, was also normal. The asymptomatic character of these MS cases can be explained first by the location of the plaques and the lack of spinal cord and optic tract involvement. It could also be due to the small size of the plaques and to axonal preservation. Such features are rare since our 3 observations have been selected from a pathological collection of 125 MS cases and 9,300 general neuropathological records. Six other cases have been previously reported by other authors.