en عمومى General پژوهشي Research Abstract Background: Multiple sclerosis (MS) is a central nervous disease that may cause disability. Depression is very common in MS which has a negative impact on quality of life and cognitive status. This study was designed to determine the prevalence of depression in MS patients, to assess the association of neuropsychological, demographic factors and clinical features of it. Methods: This study was performed on 220 patients. A questionnaire was completed by patients and Beck Depression Inventory (BDI-II) test was used to evaluate the severity of depression. Results: 81.3% of patients had depression based on the cutoff point of 13. A significant relationship was found between gender, treatment duration, motion disability, Cerebellar and pyramidal symptoms and severity of depression,also between history of depression and prevalence of it. The prevalence of depression was more in age group of 20-40. No significant association was found between the duration of disease and severity of depression and demonstrated an inverse relationship between depression severity and level of education. Conclusion: We conclude, future studies should use a structured interview based on the DSM to assess patients' mood. Multiple sclerosis, prevalence, Depression, neuropsychological, interview 338 343 http://intjmi.com/browse.php?a_code=A-10-1-105&slc_lang=en&sid=1 Fatemeh Hosseini 10031947532846002488 10031947532846002488 No Assistant Prof of Psychiatry, Department of Psychiatry, Shahid Sadoughi University of Medical Sciences, Yazd, Iran Parisa Ayatollahi 10031947532846002489 10031947532846002489 No Assistant Prof of Neurology, Department of Neurology, Shahid Sadoughi University of Medical Sciences, Yazd, Iran. Nasim Behniafard 10031947532846002490 10031947532846002490 No General Practitioners, Otorhinolaryngology research center, Shahid Sadoughi University of Medical Sciences, Yazd, Iran Mohammad Nadi 10031947532846002491 10031947532846002491 Yes Assistant Prof of Psychiatry, Department of Psychiatry, Shahid Sadoughi University of Medical Sciences, Yazd, Iran Farimah Shamsi 10031947532846002492 10031947532846002492 No Msc in Biostatics, Biostatic And Epidemiology Department, The School of Heath, Shahid Sadoughi University of Medical Sciences, Yazd, Iran Amir Hossein Ferdousian 10031947532846002493 10031947532846002493 No Student of Medical School, Shahid Sadoughi University of Medical Sciences, Yazd, Iran