We examined the neurofilament heavy subunit (NEFH) as a candidate gene for familial amyotrophic lateral sclerosis. We screened the KSP repeat region of the NEFH gene in 117 unrelated individuals who inherited familial amyotrophic lateral sclerosis as an autosomal trait but who do not have the mutation in the SOD1 locus, and we found no variants in any individual. We conclude that the motor neuron degeneration observed in non-SOD1 familial amyotrophic lateral sclerosis is not due to mutations in the KSP repeat of the NEFH gene.