We reported the basic concept of the pathology of leukodystrophy with emphasis on Krabbe disease. First, the normal process of myelination and the pathology of demyelination will be described, emphasizing the course inducing neuro-inflammation in its progression. After classifying metabolic leukodystrophy, the features of Krabbe disease (globoid-cell leukodystrophy) are explained as well as molecular cloning and mutation analysis of the galactocerebrosidase (GALC) gene. Finally, the experience of hematopoietic stem cell transplantation for patients with Krabbe disease is reported and the future possibility of therapy for the disease is summarized.