Our aim was to determine the methylenetetrahydrofolate reductase (MTHFR) C677T polymorphism in hypertensive disorders during pregnancy. We conducted our experiments on isolated DNA samples of 73 healthy pregnant, 101 severe pre-eclamptic and 63 HELLP syndrome women in this study. The MTHFR C677T polymorphism was determined by quantitative real-time PCR method. A significantly higher number of the TT genotype (25.4%) was found in the HELLP syndrome group compared to the healthy (8.2%) and severe pre-eclamptics group (8.9%) (P=0.03). The frequency of the mutant T allele was found to be 45.2% of HELLP syndrome, whereas it was 32.2% of the healthy pregnant (P=0.03) and 30.2% (P=0.008) of the severe pre-eclamptic patients. In the HELLP group a high frequency of eclampsia was observed (12.6%) and among them 75% had the MTHFR C677T mutation.