To evaluate seizure characteristic among multiple sclerosis patients with coexistent seizure activity compared to control group.This study is a cross-sectional study which was conducted by reviewing the clinical records of patients with definite diagnosis of MS according to McDonald's criteria from March 2007 to June 2011, who referred to the MS clinic of the university.A total of 920 patients with a diagnosis of MS were identified, among whom 29 patients (3.15%) with seizure activity (case) due to MS with the mean age of 32.6 ± 6.23 years were analyzed. Also, fifty MS patients without any seizure occurrence with the mean age of 33.7 ± 7.4 years were used as our control group. In case group, seizure was general tonic clonic in 23 patients (79.3%), complex partial in four (13.8%), and simple partial in two (5.9%). The 26 available interictal EEGs in MS patients showed abnormal EEG pattern in 22 (84.6%) of them, including focal epileptic form discharge or focal slowing in 10 (38.5%), generalized discharge (spike-wave, polyspike, or general paroxysmal fast activity) in 10 (38.5%), and general slowing activity in 10 record (38.5%). MRI reviews of the 26 available brain MRIs showed subcortical white mater lesions in 22 (84.6%) of patients with seizure. All MRIs were performed within one month after the first seizure episode. Amongst 48 available MRIs in our control group, 91.7% (44 cases) showed periventricular lesions and in 8.3% (4 cases) subcortical white matter lesions were reported.The result of this study demonstrated the higher rate of subcortical whit matter lesion in MS patients with seizure occurrence compared to control group.