Mutations of the neurofilament-light (NEFL/NF-L) gene were examined in 124 unrelated Japanese patients with Charcot-Marie-Tooth disease (CMT) without known gene mutations, and 248 normal Japanese individuals. A new method, which can detect basepair mismatches with RNase cleavage on agarose gel electrophoresis, coupled with DNA sequencing, identified 8 novel sequence variations in the NF-L gene. In these sequence variants, 5 variants were polymorphisms, including 3 single nucleotide polymorphisms (SNPs), and 3 other missense mutations (Pro22Thr, Asn97Ser and Ala148Val) were found in the patients with CMT phenotype. The variant alleles in the NF-L gene could influence the developing process of CMT phenotype and also might cause CMT phenotype.