Krabbe's disease (globoid cell leucodystrophy) is a disorder involving the white matter of the peripheral and central nervous systems. Mutations in the gene for the lysosomal enzyme galactocerebrosidase (GALC) result in low enzymatic activity and decreased ability to degrade galactolipids found in myelin. The disease is classically of infantile onset, but adult onset cases have been reported. Magnetic resonance imaging (MRI) of the brain shows characteristic abnormalities. A unique family with Krabbe's disease is described, with proven GALC deficiency but normal MRI. A neurological phenotype is present in heterozygotes and the family shows the extent of homozygotic phenotypic diversity that can be seen in this disorder.