Thirty cases of amyotrophic lateral sclerosis (ALS) supported by respirators for more than 1 year beyond respiratory failure were followed to estimate the progression of their voluntary motor impairment. The extremities were apt to be affected within two years of the onset of the disease, but complete voluntary paralysis occurred in less than half of the cases (14/30), more frequently appearing after respiratory failure. Respiratory and bulbar paralysis were closely related, and combined complete voluntary paralysis of these muscle systems was observed in 25/30 cases. Incomplete external ophthalmoplegia also increased after respiratory failure, but complete voluntary external ophthalmoplegia was rare (5/30).