Background: Maternal type 1 diabetes is associated with an increased risk for fetal malformations. The mechanism by which diabetes caused teratogenic disorders is not fully known. Previous studies have demonstrated that many teratogenic diabetic cases were related to free radical oxygen species. This study was conducted to evaluate the effect of maternal diabetes on both embryo and placenta by estimating the oxidative and DNA damage in embryo and placenta of diabetic mellitus- induced rats. The possible role of olive leaves extract of Olea europaea ( O. europaea ) plant in repairing the damage was also assessed. Material and Methods:. Diabetes mellitus was induced by streptozotocin (STZ) by a single intraperitoneal injection (35 mg/kg b wt). O.europaea leaves water extract was administered orally (550 mg/ 100g b wt/ day) for 5days before pregnancy and18 days after. Malondealdehyde (MDA) level, glutathione peroxidase (Gpx) and superoxide dismutase (SOD) activities and glycogen concentration were measured in term embryo and placenta homogenates of diabetic and control rats. Moreover, the evaluation of DNA damage was carried out by the Alkaline Comet Assay using embryos and placentas taken from STZ-induced diabetic and control pregnant rats. Results: the results showed an elevation in MDA level of the diabetic groups of both embryo and placenta compared to that of the control. This was accompanied by reduction in Gpx and SOD activities indicating oxidative damage. Glycogen level was reduced in diabetic groups of embryo and placenta. Both oxidative and hyperglycemic status were improved in the groups treated with olive leaves water extract. The percentage of tail DNA and tail moment values were also higher in both embryo and placenta of the diabetic -induced rats. DNA damage seems to be partly ameliorated in groups treated with O. europaea leaves water extract. Conclusion: This study indicated that maternal hyperglycemic condition in diabetic- induced pregnant rats could generate oxidative and DNA damage to embryo and placenta that could be ameliorated by oral doses of olive leaves water extract.