A meta-analysis was conducted to assess the relationship between serum homocysteine, vitamin B 12 , and folate levels in patients with multiple sclerosis (MS). The DerSimonian and Laird Q test was used to evaluate the degree of heterogeneity between studies and a funnel plot was used to assess publication bias. The pooled effect size (standardized mean difference [SMD]) between patients with MS and control patients) from a random effects model was 0.84 (95% confidence interval: 0.18, 1.49) for homocysteine and –0.25 (–0.45, –0.04) for vitamin B 12 , and from a fixed effects model was 0.98 (0.80, 1.16) for homocysteine and –0.25 (–0.41, –0.09) for vitamin B 12 . Both nutrients were statistically significant, but the SMD for folate was not. Patients with MS were found to have raised homocysteine levels but low B 12 levels, which might contribute to the pathogenesis of MS.