Background: Gestational diabetes defined as abnormal glucose metabolism with the first recognition during pregnancy and usually resolves after the birth. Aim of the study to evaluate the effect of instructional package on knowledge and self-care practices among gestational diabetic women. Research design: A quasi-experimental study design (one group) was used to fulfill the aim of study. Research setting: This study was conducted at obstetrics and gynecological outpatient clinic and Obstetrics and Gynecological department in Benha University hospital. Study subjects: A purposive sample of 64 pregnant women medically diagnosed with gestational diabetes. Tools of data collection: Three tools were used for data collection: Tool (I): A structured interviewing questionnaire sheet, Tool (II): Maternal knowledge questionnaire, Tool (III): Diabetic Self-Care Practices questionnaire. Results: There was a highly statistical significant difference between the result of the post intervention and follow up phases compared with pre intervention about knowledge and self-care practices regarding gestational diabetes. Conclusion: There was a marked improvement in pregnant women' total knowledge and self-care practices regarding gestational diabetes after implementation of the instructional package. Recommendations: Development of a training program and evidence based interventions to provide a better view of the women health promotion strategies related to gestational diabetes.