We aimed to investigate the potential harmful effects of maternal valproic acid (VPA) on fetal sciatic nerve, and the protective effects of vitamin E (Vit E) and folic acid (FA) on fetal rats. Valproic acid (400 mg/kg), folic acid (400 mg/kg) and vitamin E (250 mg/kg) were administered to rats on each of gestation days 8-10. All fetuses were collected on gestation day 20. With thin sections of biopsies, sciatic nerve of fetuses were stained with uranyl acetat and were examined under transmission electron microscope. The fetuses (n:36) were divided into five groups: control, vpa, vpa+fa, vpa+vit e and vpa+fa+vit e groups. In each group; drug procedure, surgical procedure and histological methods were performed. Later, weights and lengths of fetuses in each group were compared and analyzed by One-Way Anova test. Administration of single doses of valproic acid (400 mg/kg) resulted in weight and length loss between control and vpa group. However, length and weight differences between the other groups were not significant. The histopathological findings of control group was normal. In vpa group, it showed extensive degenerative changes especially in myelin coat. In addition, most prominent finding in this group was condensation of collagen fibers in extensively demyelinated samples, while moderately effected areas were relatively normal. Both vpa+fa and vpa+vit e groups exhibited similar ultrastructural changes, reflecting minimal to moderate degenerative changes. In vpa+fa+vit e group had almost the normal structure. Administration of single doses of valproic acid (400 mg/kg) resulted in a deteriorative effect on sciatic nerve at ultrastructural level. Administration of FA and Vit E had a protective effect to prevent the degenerative changes to a certain degree. Combination of FA and Vit E together following VPA administration had a more potent protective effect. The objective of the present study is to analyze histopathologic changes which may occur in a high risk experimental model after the administration of valproic acid. In addition, protective roles of the administration of folic acid and vitamin E are assessed.