Multiple sclerosis (MS) is a disease of the nerve system with degerative myelin sheath of nerve cells in the brain and spine causing disorder of signal transmission. This study determined the presence of N9, N13, N20 and describing abnormality of those three waves in MS patients. Somatosensory evoked potential (SEP) was recorded after stimulating the medial nerve in 30 MS patients. The results showed that N9 was recorded in almost patients (99.3 percent), but neither for N13 nor N20. Abnormal N13 and N20 appeared in 80 percent and 86.67 percent of the patients, respectively. The abnormal SEPs were mainly unilateral or bilateral absence of N13 and N20.