We report a patient with a 3-year history of brief episodes of electrical sensations over her back and upper limbs that occurred during Tai-Chi practicing. This appearance of Lhermitte's sign was later followed by additional neurologic symptoms, and the patient was diagnosed as suffering from multiple sclerosis. Though the patient related the Lhermitte's sign to her ability to achieve full relaxation in Tai-Chi exercise, we think it was the first manifestation of the disease.