We report a characteristic finding in gadolinium-enhanced magnetic resonance images (MRIs) of the central nervous system (CNS) in a 61-year-old man with a homozygous transthyretin (TTR) Val30Met mutation. Although he presented with polyneuropathy accompanied by autonomic dysfunction and vitreous opacities in both eyes, he has shown no overt signs or symptoms of CNS involvement. Total protein level in the cerebrospinal fluid was moderately elevated. In the gadolinium-enhanced T1-weighted MRIs of the brain and spinal cord, leptomeningeal enhancement was seen along the surfaces of the brain stem and more clearly in the spinal cord, suggesting leptomeningeal TTR-related amyloid deposition. Our result indicates that gadolinium-enhanced MRI of the CNS may be a very sensitive and useful method for detecting leptomeningeal amyloid deposition, since abnormal findings can be detected even at a presymptomatic stage of CNS involvement.