Background: gestational diabetic women are reported to be high risk for infections of the genital tract. Controlling vaginal infections rested on the nurse through educating women self-care practices. Aim: To assess the effect of educational program about self-care practices on prevention occurrence of vaginal infection among gestational diabetic women. Methods: Quasi experimental research design was used in this study. It was conducted at antenatal outpatient clinic of South Valley University's Hospital. Sample included 60 pregnant women with diabetes mellitus. Structured interview and self-care model was used and involved three parts. An educational program about care of genital system was carried out on pregnant women with gestational diabetes. Results: There is statistical significant difference between control and study groups regarding total self-care practices and occurrence of genital infection Pvalues are 0.001. Conclusion: There was a vital role to the educational program about self-care practices on preventing occurrence of vaginal infection among pregnant women. Recommendations: Planning and implementing educational program as a routine hospital care with providing a brochure about genital hygienic practices are important to reduce rate of vaginal infection among gestational diabetes women.