Background: Preeclampsia is a serious problem with unknown etiology in pregnancy. The inheritance of preeclampsia is one of the theories regarding to the etiology of preeclampsia.Methylenetetrahydrofolate Reductase (MTHFR) is a key enzyme in folate metabolism and C677T polymorphism of the MTHFR gene is associated with decrease in MTHFR activity, therefore blood levels of homocysteine increase which leads to vascular disease and also preeclampsia. The aim of this study was to evaluate the correlation between MTHFR gene C677T polymorphism and preeclampsia.Materials and method: This case-control study was performed on 129 preeclamptic pregnant women and 125 control individuals. The C677T polymorphism of MTHFR gene was determined by PCR-RFLP method.Results: Frequency of CC, CT and TT genotypes of MTHFR C677T gene polymorphism were respectively 57.4, 38.8 and 3.9 percent in preeclamptic women and 53.6, 40 and 6.4 percent in control group that showed no significantly difference (p=0.614). However, the frequency of TT genotype was higher in control group (p=0.36). There was not any significant difference in T allele distribution between preeclamptic women (23.3%) and control group (26.4%).Conclusion: There was not any correlation between C677T polymorphism and preeclampsia but the TT genotype seems to have a protective role in preeclampsia.