Background: Antioxidants such as vitamin C can eliminate free radicles responsible for oxidative stress. Objective: To assess the serum level of vitamin C in a sample of multiple sclerosis (MS) patients to investigate a possible role of vitamin C in the pathogenesis of MS. Subjects and Methods: Forty patients with MS and twenty healthy controls were included in this study. Vitamin C level was estimated for each participant. Results: Serum vitamin C levels were significantly lower among the patients (ranging from 0.28 mg/dL to 0.75 mg/dL with mean 0.47 ± 0.14 mg/dL and median of 0.46 mg/dL) compared to controls (ranging from 0.60 mg/dL to 2.90 mg/dL with mean 1.87 ± 0.61 mg/dL and median of 1.90 mg/dL) (P Conclusion: Patients with MS tended to have low serum vitamin C levels, and younger patients had lower serum levels.