Recent genetic and immunohistochemical analyses have shown that Miyoshi myopathy (MM) is caused by a mutation in the DYSF gene, which induces dysfunction of dysferlin. The author described one patient showing characteristic MM phenotype with deficiency of dysferlin on immunohistochemistry. Direct DNA sequencing of whole exons of DYSF gene revealed one homozygous missense mutation (G1165C) on exon 12, which let to an amino acid substitution from the glutamic acid to glutamine at the 389 of the peptide sequence in this patient. This is the first reported case of MM confirmed by immunohistochemical and genetic analyses in Korea.