Gestational diabetes mellitus (GDM) defined as is a disease with hyperglycemia, insulin resistance and fetal abnormality development. This study was designed to evaluate the hypoglycemic effect and hepatoprotective properties of olive leaves extract. The experimental ISSN 2157-6076 2017 mice divided into, the control group GI (not diabetic group), and the diabetic pregnant mice groups were divided into: the diabetic pregnant group (GII) single intraperitoneal injected by streptozotocine (STZ, 240mg/Kg b.wt.). The pregnant mice were given a daily oral dose of olive leaf extract (OLE) only (100 mg/kg) from day 1 to 18 of gestation group (GIII). The diabetic pregnant mice were given daily oral dose of olive leaf extract from day 1 to day 18 of gestation, group (GIV). The STZ-induced diabetic group(GII) exhibited a significant (p<0.05) hyperglycemia, accompanied with a significant increase in serum aspartate aminotransferase (AST) and alanine aminotransferase (ALT), enzyme activities when compared with control group. This result is confirmed with extreme histopathological changes in liver tissues and decreased in glutathione peroxidase (GPx) expression. A significant improvement in glucose level, serum AST and ALT enzyme activities showed in (GIV). Also, OLE succeeded to minimize the severe changes in liver tissues of diabetic pregnant mice and their fetuses. Furthermore, level of (GPx) was returned to near normal level. The findings suggest that OLE have a hepatoprotective effect on pregnant diabetic mice and their fetus. Journal of Biology and Life Science