The clinical and pathological findings in an unusual case of sporadic juvenile amyotrophic lateral sclerosis (ALS) are presented and the four other autopsied cases of this disorder reviewed. In many respects the sporadic adult and juvenile disease are similar. However, in three of the juvenile cases including our own neuronal inclusions derived from Nissl substance formed as a result of the disease process. These inclusions are not seen in sporadic adult ALS and differ from those associated with other motor neuron diseases. Neurofibrillary degeneration was seen in our own case and in one other juvenile case. The distribution of the neurofibrillary changes differed from the pattern observed in cases of ALS where neurofibrillary degeneration is known to occur. Our observations suggest that sporadic juvenile ALS is a distinct entity and not simply an extension of the sporadic adult disease.