Background: Gestational Diabetes is associated with severe maternal, fetal and neonatal complications. Health education about regular exercises, dietary adjustment and proper taking of medication is important part in the care of women with gestational diabetes. Nurses have a significant role in educating women how to prevent and reduce gestational diabetes adverse effects on pregnancy outcomes. Aim: This study aimed to assess the effect of educational sessions on knowledge, attitude and self -care practices among pregnant women with gestational diabetes. Methods: A quasi experimental pretest/posttest research design was used at the antenatal outpatient clinics of Mansoura University Hospitals, Egypt. A purposive sample of 97 gestational diabetic women was studied, who aged 18 – 35 years, gestational age 24 – 27 weeks, have single live fetus. Data was collected for pregnant women knowledge about gestational diabetes using gestational diabetes knowledge questionnaire, pregnant women attitudes regarding gestational diabetes using diabetic attitude scale and pregnant women self-care practices using diabetic self-care practices questionnaire. Results: Post intervention, pregnant women had good knowledge score (77.3%), improved total positive attitudes score (91.8%) and improved total good self-care practices score (90.7%) regarding gestational diabetes. There were statistically significant differences (p < 0.001). Conclusion: The current study hypotheses were accepted where pregnant women’s knowledge, attitude and self-care practices regarding gestational diabetes were improved after implementation of the educational sessions. There were statistically significant differences between those variables before and after the intervention. Recommendations: The current study recommended that, simple clarified educational programs should be continuously implemented to increase women’s knowledge and improve their attitude about gestational diabetes as well as promote their self-care practices and lifestyle. Also, training courses and workshops about gestational diabetes care and management for health care providers at antenatal units should be conducted on regular intervals.