We report a patient of Charcot-Marie-Tooth disease (CMT) accompanied by transient splenium abnormality in brain MRI. A 34-year-old man suffered from chronic progressive unsteadiness and sensory disturbance of all limbs. Neurological examination showed muscle weakness and atrophy in the distal extremities with pes cavus, mild sensory disturbance of four extremities and generalized decreased reflexes. The nerve conduction study described the presence of sensory-motor polyneuropathy. We could not investigate his GJB1 gene. However, we suspected that he was X-linked CMT (CMTX), because his electrophysiological findings showed intermediate slowing of MCV, and auditory brain-stem response (ABR) demonstrated central conduction slowing. Brain MRI revealed the abnormal high signal intensity in the splenium of the corpus callosum on T2-weighted image. This lesion diminished two months later without any treatment. Recently, there had been reported transient splenium abnormality in CMTX cases, and there were clinical similarities between the cases of these reports and our case. We considered that the pathophysiology of this case was the disruption of gap junction communications expressed between oligodendrocyte and astrocytes induced by connexin 32 (Cx32) mutations. Furthermore, the transient functional disturbance of astrocytes would be another pathophysiologic mechanism of splenium abnormality.