A missense mutation (Gly93-->Ser) was identified in exon 4 of the Cu/Zn superoxide dismutase (SOD1) gene of a 48-year-old Japanese man with familial amyotrophic lateral sclerosis (FALS). The SOD1 activities in the fibroblasts and in a lysate of erythrocytes of the patient did not differ from those of healthy controls. The clinical characteristics of the patient were fairly slow progression of the illness, prominent sensory impairment, urinary disturbance and blood pressure fluctuation due to sympathetic hyperactivity. The severe sensory and autonomic disturbances, association of which with FALS has not been previously reported, may represent specific clinical features associated with the Gly93Ser mutation or may indicate the variability of clinical findings even in patients with the same mutation.