Background: Gestational Diabetes Mellitus (GDM) is one of the most commonmedical health problems that may occur during pregnancy and may lead to a range ofshort and long-term maternal, fetal as well as neonatal complications. However, recentresearches have revealed that, walking exercise has been considered as a ‘gold standard’in controlling blood glucose level and body mass index among gestational diabeticwomen.Aim: The study was conducted to evaluate the effect of walking exercise oncontrolling blood glucose level and body mass index among gestational diabetic womenSubjects and method: A quasi-experimental study design was utilized at Antenatal Clinic ofObstetric and Gynecological Specialty Center at Mansoura University Hospitals,Mansoura city. A purposive sample conducted on 126 pregnant women diagnosed withgestational diabetes mellitus, The study sample was divided into two groups,interventiongroup (n= 63):practiced walking exercise in addition to routine antenatal care and controlgroup (n= 63): followed routine antenatal care only.Tools: Two tools were used to collectdata from participants as a structured interview schedule and maternal assessment record.Results:The current study resultsindicated that, there was a highly statistical significantreduction of body mass index and the mean random blood glucose levels at 34 & 37 weeks'of pregnancy after intervention in the walking exercise group than control group (p <0.001). ConclusionandRecommendations: This study showed that, pregnant women withgestational diabetes mellituswho practiced walking exercisehad improved blood glucoselevel and body mass index than those who did not. It is recommended that, pregnantwomen with gestational diabetes mellitusshould practice walking exercise duringpregnancy as one of the significant modalities to improve blood glucose level and bodymass index.