Objective: To determine the relationship between hyperhomocysteinemia and multiple sclerosis (MS).

Methods: Cochrane, Medline, EMbase, Springerlink, Highwire, CBM, CNKI and some other databases were searched for literatures. Articles were identified using the Medical Subject Heading term "hyperhomocysteinemia, homocysteine, multiple sclerosis". The methodological quality of internalized literatures were evaluated, screened and heterogeneity tested. Case control studies involving unrelated subjects and valid data were extracted and analyzed in Stata 8.0.

Results: Nine studies were included in this review. The involved 1146 subjects were made of 676 patients and 470 controls. A meta-analysis showed that the level of homocysteine in MS was higher than that in controls (standardized mean difference 1.25, 95%CI: 0.48 - 2.01). The analytical result of sensitivity proved that the result of meta-analysis was coherent.

Conclusions: Hyperhomocysteinemia is associated with MS, and it may contribute to the pathological course of MS.