BACKGROUND: Mutations in the myelin protein zero (MPZ) gene, which is located on chromosome 1q21-q22, is present in Charcot-Marie-Tooth disease type 1B (CMT1B), CMT type 2, Dejerine-Sottas syndrome, and congenital hypomyelination neuropathy. It is proposed that the nature and position of the MPZ mutations mainly determine the axonal and demyelinating phenotypes. In this study, we investigated to determine the clinical and electrophysiological characteristics in CMT patients with mutations in the MPZ gene. METHODS: We examined mutations of MPZ, in 62 Korean families diagnosed as having CMT disease. Mutations were confirmed by through both strands sequencing. Nerve conduction studies were carried out in CMT patients having each mutation. RESULTS: The three mutations (Asp118Asn, c.449-1G>T (3'-splice site), Lys236Glu), determined to be novel, were not detected in the 105 healthy controls. The mutation frequency of MPZ was similar as those found in several European populations. Electrophysiologically, 3'-splice site mutation (449-1G>T) showed the conduction block and moderate slowing nerve conduction velocities like that of CMT1B. However, the other mutations represented the electrophysiological features of CMT type 2. CONCLUSIONS: We report the identified three novel MPZ mutations in Korean CMT patients and the phenotype-genotype correlations based on nerve conduction studies.