Background: Multiple sclerosis (MS) is a chronic inflammatory demyelinating and neurodegenerative disease of the central nervous system with unknown causes. In the last decade, the prevalence of MS in Iran has increased. Objectives: This study evaluated the frequency of familial MS among patients in the Hamadan society for MS. Patients and Methods: This cross-sectional study was performed on 1202 MS patients in Farshchian hospital, Hamadan, in 2013. All patients were diagnosed with definite MS. A questionnaire was used to gather information; demographic characteristics, medical history, signs and symptoms at onset, course of disease, relatives with MS, and degree and type of relationship were recorded.