Background: Gestational Diabetes Mellitus is a pregnancy-related complication that is on the rise internationally and linked to bad health outcomes for both mothers and the unborn child.  5 A's model is a realistic, evidence-based approach created to modify behavior, achieve self-management, and enhance pregnancy outcomes. Aim:  was to investigate the effect of self-management program based on 5A's model for gestational diabetic women on maternal and neonatal outcomes. Methods: A quasi-experimental research design was used at antenatal clinic of Obstetrics and Gynecological department in Benha University Hospital. A purposive sample of 85 pregnant women diagnosed with GDM.  Tools: four tools were used : A structured Interview Schedule, Gestational Diabetic Attitude Scale, Gestational Diabetes Self-Management Questionnaire and Maternal & Neonatal Outcome Sheet. Results: there was a highly statistical significant differences in total knowledge score, total attitude score and total self- management ability score post intervention compared to pre intervention among studied group(p<0.001). Also, there was a statistical significant reduction in the occurrence of maternal complications in study group. Similarly, the neonates of the study group had better outcome & lower incidence for developing neonatal complications. Conclusions: Self-management program based on the 5A's model regarding gestational diabetes has a positive effect on women's knowledge, attitudes and self-management ability with favorable maternal & neonatal outcomes. Recommendations: a simple Arabic handout outlining the benefits of GDM self- management based on the 5A's model should be disseminated to all pregnant women with GDM at hospitals and maternal and child health centers to facilitate modifications in lifestyle and adherence to self-management routines, ultimately leading to enhanced outcomes in pregnancy.