2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) can cause a high percentage of cleft palate in fetuses when administered during organogenesis in certain strains of mice including C57BL/6J. In this study, folic acid (FA) was tested for antiteratogenic effects on TCDD-induced cleft palate in fetal mice. The pregnant C57BL/6J mice were dosed with 24 microg TCDD/kg and/or 5 mg, 10 mg, 20 mg, 40 mg FA/kg body weight on gestation day (GD) 10. The control group mice received 50 mL sesame oil/kg body weight on GD10. The mice were sacrificed on GD12.5, GD13.5, GD14.5, GD15.5, and GD16.5. The harvested embryos were examined to detect the incidence of cleft palate and the developing palatal shelves on different phases were investigated morphologically and histologically among different groups. Total frequency of clefts was 55.56% in TCDD group and 17.50% (5 mg), 42.85% (10 mg), 42.10% (20 mg), 28.26% (40 mg) in TCDD + FA groups. FA (5 mg) reduced the incidence of the cleft palate from 55.56% to 17.50% (p = 0.005). There were no significant differences between the TCDD group and 10 mg, 20 mg, 40 mg TCDD + FA groups. Based on the these results, the present study suggests that FA can reduce the incidence of 2,3,7,8-TCDD-induced cleft palate in mice.