Two women (patient 1, 77 years old, and patient 2, 63 years old) with strong clinical evidence for corticobasal degeneration (CBD) are presented. Patient 2 was in an early stage of the disease with only a mild disability of her left hand. In addition to the clinical characteristics, both patients presented the typical cortical reflex myoclonus. Magnetic resonance imaging studies for both patients revealed nearly identical hyperintense lesions somatotopic from the left-hand primary motor cortex (M1), extending to the midline and possibly supplementary motor area (SMA) in patient 2. To our knowledge, this has not been previously described in patients with CBD. These lesions may play a role in the etiology and the development of CBD with involvement of the M1 and may correspond to the underlying pathology of demyelination or gliosis.