This study was performed to investigate effects of dietary folic acid supplementation on plasma homocysteine levels, thiobarbituric acid reactive substance s (TBARS) level s and liver SAM/SAH ratio in hyperhomocysteinaemia-induced pregnant rats. Forty-two female Sprague-Dawley rats were divided three groups (C: control diet, HFD: $0.3\%$ homocystine and 0 mg folic acid diet, HFS: $0.3\%$ homocystine and 8 mg/kg folic acid diet) according to homocystine and folic acid levels in the diet. They were fed experimental diets for 5 weeks prior to the mating and also during the entire period of pregnancy till gestational day 20. Dietary folic acid supplementation caused a significant decrease in plasma homocysteine levels which had been increased by a homocystine-diet, with a concomitant increase in plasma and liver folate levels. Liver TBARS levels in homocysteine-folic acid-deficient group (HFD) were higher than those in control group. Dietary folic acid supplementation increased hepatic SAM/SAM ratio in homocysteine-folic acid- sopplemetantion group (HFS) when compared to the HFD (p < 0.05). These data suggest that folate depletion and elevated plasma homocysteine may promote oxidative stress in rat livers and influence the remethylation cycle of the homocysteine metabolism detrimentally. In conclusion, dietary folic acid supplementation was found to be effective for lowering plasma homocysteine levels, relieving oxidative stress, and improving the methylation status in the body.