The C677T polymorphism of the methylenetetrahydrofolate reductase (MTHFR) gene was implicated to be associated with hypertension due to its role in catalyzing the formation of 5-methylenetetrahydrofolate, a co-substrate for the conversion of homocysteine to methionine. Association studies were reported in different populations; however, a great number of subsequent studies have produced contrary results, possibly reflecting inadequate statistical power. With the cumulative data in recent years in both Caucasian and Asian populations, it was necessary to carry out a comprehensive analysis of previous findings. In this meta-analysis, we combined 26 English and Chinese studies in Caucasian and Asian populations published up to November 2006 to give a new picture of the role of the C677T polymorphism in the MTHFR gene. Evidence of significant association was detected between C677T polymorphism and hypertension in both populations. Additionally, the significant association between C677T polymorphism and hypertension/hypertension-in-pregnancy suggested that this polymorphism was one independent risk factor of hypertension.