Background: Breast engorgement means that the mother’s breasts become overfull due to failure to remove breast milk effectively or frequently enough. Aim of the study: Was to evaluate the effect of prenatal teaching program on knowledge regarding prevention of breast engorgement among primiparous women. Study design: Quazi experimental design. Setting: The study was conducted at the outpatient antenatal clinic at Zagazig University Hospital. Study subjects: A purposive sample of 70 primiparous women was included in the study. Tools of data collection: Two tools were used; Structured interview questionnaire, questionnaire of knowledge of primiparous women regarding breast feeding and breast engorgement. Results: After implementation of the prenatal teaching program there was highly statistically significant increase in primiparous women knowledge regarding the prevention of breast engorgement, as for relation between obstetric history of the studied primiparous women and their total knowledge, there was statistically significant relation between total primiparous women’ knowledge at pre-intervention and their number of antenatal visits at (P= <0.05). There was no statistically significant relation between total primiparous women’ knowledge at post-intervention and their number of abortions and mode of delivery at (P= <0.05). Conclusion: the research hypothesis was achieved as the majority of the primiparous women had good knowledge regarding prevention of breast engorgement after implementation of the teaching program. Recommendations: At the antenatal care units it is required to conduct a training health intervention regarding breast engorgement and how to prevent it for maternity nurses in order to educate the women about this topic, which is a crucial aspect of women’s health