Background: Vitamin D deficiency has been proposed as risk factors of cerebrovascular stroke. Objectives: The aim of this study was firstly, to assess the serum level of vitamin D in cerebral stroke patients and secondly to examine if its deficiency was associated with stroke severity and outcome. Methods: We utilized a case-control study design and recruited 138 acute stroke patients and 138 age- and sex-matched controls from subjects attending outpatient clinic for other reasons. All participants were subjected to full general and neurological examination. Brain imaging CT and/or MRI was performed. Blood samples were collected for measurement of serum level of vitamin D (ng/ml) by ELISA, Alkaline phosphatase, serum Calcium and phosphorous. The stroke severity was assessed by National Institutes of Health Stroke Scale (NIHSS) and stroke outcome was assessed by modified Rankin Scale (mRS). Results: Stroke patients had significant lower levels of vitamin D compared to the control group. Vitamin D deficiency remained significantly associated with the NIHSS stroke severity score and the mRS 3-month stroke outcome after controlling for other significant factors using multivariable logistic regression analysis. Furthermore, ROC curve analysis of vitamin D serum level that best predict stroke severity and outcome was ≤ 9 ng/ml. Conclusion: Our results demonstrated that stroke patients suffer from vitamin D deficiency, which was associated with both stroke severity and poor outcome. Vitamin D supplementation could exert a therapeutic role in the management of cerebral stroke. Keywords: Vitamin D, stroke, NIHSS, mRS.