Tehran University of Medical Sciences Current Journal of Neurology 2717-011X 14 1 2015 03 15 17 21 Masoud Nikanfar Department of Neurology, Neuroscience Research Center, Imam Reza Hospital, Tabriz University of Medical Sciences, Tabriz, Iran. Ali Akbar Taheri-Aghdam Department of Neurology, Neuroscience Research Center, Imam Reza Hospital, Tabriz University of Medical Sciences, Tabriz, Iran. Maria Yazdani Department of Neurology, Neuroscience Research Center, Imam Reza Hospital, Tabriz University of Medical Sciences, Tabriz, Iran. Sheida Shaafi Department of Neurology, Neuroscience Research Center, Imam Reza Hospital, Tabriz University of Medical Sciences, Tabriz, Iran. Nooshin Masoudian Department of Neurology, School of Medicine, Tabriz University of Medical Sciences, Tabriz, Iran. Hossein Akbari Department of Neurology, School of Medicine, Tabriz University of Medical Sciences, Tabriz, Iran. Parisa Youhanaee Department of Neurology, School of Medicine, Tabriz University of Medical Sciences, Tabriz, Iran. Hamzeh Abbaszadeh Department of Nutrition, School of Nutrition and Health, Tabriz University of Medical Sciences, Tabriz, Iran. 2015 10 14 Background: It seems that serum vitamin D levels are one of the potential environmental factors affecting the severity of multiple sclerosis (MS). In this study, we aim to evaluate vitamin D levels in MS patients and healthy subjects and assess the relationship between vitamin D level and disability. Methods: In this case-control study, 168 rapid relapsing MS patients and 168 matched healthy controls were randomly included in this study. Demographic characteristics and serum vitamin D levels for patients and controls, as well as expanded disability status scale (EDSS), duration of disease and diagnostic lag for patients were evaluated. We followed up patients for 6 months and relapses were recorded. Results:  The  mean  serum  vitamin  D  levels  were 19.16 ± 17.37 inpatients and 25.39 ± 19.67 in controls (P = 0.560). The mean serum vitamin D levels were 12.65 ±  13.3 in patients with relapses and 22.08 ± 18.22 in  patients without any relapses (P < 0.001). There  was  no  significant  correlation  between  E SS score and serum vitamin D levels (r = −0.08, P = 0.280). There  was  a  significant  positive  correlation  between EDSS score and disease duration (r = 0.52, P < 0.001). Conclusion: In conclusion, vitamin D level in patients with  MS  was  significantly  lower  than  the  healthy subjects,  but  no  significant  relationship  was  found between vitamin D levels and disability.  Our findings did not suggest a protective role for serum vitamin D levels against disability. https://ijnl.tums.ac.ir/index.php/ijnl/article/view/578 https://ijnl.tums.ac.ir/index.php/ijnl/article/download/578/224