Background: Mutations in the kerato-epithelin gene on chromosome 5 q 31 are known to cause four distinct autosomal dominant diseases of the human cornea: Reis-Bucklers, granular, lattice, and Avellino corneal dystrophy. Mutation of arginin to glutamine in codon 555 (R 555 Q) in kerato-epithelin was recently reported in four blood-related patients with Reis-Bucklers corneal dystrophy.Case: A 42-year-old female has had photophobia with decreasing vison since the age of 20 years. Her corrected visual acuity was 0.5 in both eyes. She showed subepithelial opacities in both corneas characteristic of Reis-Bucklers corneal dystrophy.Method: The DNA was extracted from leukocytes according to standard protocols. The keratoepithelin gene was examined for a mutation by the polymerase chain reaction and direct sequencing.Findings: We identified kerato-epithelin mutation R 555 Q. The patient's two children and 50 controls did not show missense mutation.Conclusion: Kerato-epithelin mutation R 555 Q was present in a Japanese patient with Reis-Bucklers corneal dystrophy.