Adult-onset Krabbe disease is an autosomal recessive degenerative leukodystrophy that presents with bilateral corticospinal tract involvement on MRI. Although peripheral nerve involvement is a known manifestation of Krabbe disease, MRI findings of peripheral nerve abnormalities are limited to the cranial nerves and spinal nerve roots. In this case report, we discuss two cases of adult-onset Krabbe disease with brachial plexus enlargement on MRI. Adult-onset Krabbe disease should be included in the differential diagnoses when brachial plexus enlargement and white matter lesions involving corticospinal tracts present simultaneously.