Krabbe disease is an autosomal recessive neurodegenerative disorder that affects both the central and peripheral nerve system due to an enzymatic defect of galactocerebroside bata-galactosidase. The patient had typical clinical features of Krabbe disease, with irritability, hypertonicity, failure to thrive, and opisthotonic posturing. A brain MRI demonstrates profound white matter demyelination. The diagnosis of Krabbe disease is suspected on the basis of clinical pictures and confirmed by finding markedly reduced galactocerebroside bata-galactosidase activity in leukocyte or cultured fibroblast. Here we present the first reported case of Krabbe disease in Korea confirmed by decreased activity of galactocerebroside bata-galactosidase enzyme in leukocyte.