Maternal diabetes is responsible for many types of embryonic defects. Increased oxidative stress has been suggested to play a role in the pathogenesis of disturbed embryogenesis in diabetic pregnancies. The Nigella sativa seeds are used in folk medicine all over the world for treating many diseases. Regarding to antioxidant properties of Nigella Sativa, it was of interest to determine whether Nigella sativa extract has any effect on spinal cord neuroepithelium of diabetic rats' embryos. Rats were distributed to 4 groups, two diabetic and two control groups. Diabetes was induced by intrapritoneal injection of STZ. Rats were mated overnight and treatment with Nigella sativa extract or vehicle from 1 to day 17 of gestation at a dose of 1mg/kg body weight by gastric gavages. On the 17th day of gestation, rats were sacrificed. In offspring of vehicle-treated diabetic rats, a significantly decreased means (CRL) observed, in comparison with offspring of nondiabetic rats. Treatment with Nigella sativa slightly increased but did not normalize CRL compared with control group. No abnormalchanges in histology of neural tube were seen in evaluation of neural tube in all groups. Micrograph of diabetic rats treated with vehicle showed some abnormal projection on the apical surface of neuroepithelial cells. These changes were not seen in other groups. It seems Nigella sativa has a protective effect against diabetic embryopathy and fetal loss.