Iron deficiency anemia in pregnancy is a major health problem. All pregnant women are at risk for becoming anemic that is because the iron need for the mother and fetus gradually increases during pregnancy and reaches its highest level at the end of the pregnancy. Aim: To investigate the effect of educational instructions on pregnant women's knowledge and practice regarding iron deficiency anemia. Subjects and method: Design: A quasi-experimental research design was used to achieve this study. Setting: The study was applied in antenatal outpatient clinics at Mansoura University Hospitals. Subjects: A purposive sample of 300 pregnant women involved in the study from the previously selected settings. Three Tools were used for data collection 1) a structured interviewing questionnaire, 2) a pregnant women's reported practices tool, and 3) a hemoglobin level assessment sheet. Results: A statistically significant difference was detected between pregnant women's level of knowledge and practice regarding iron deficiency anemia and Hemoglobin (Hb) value after educational instructions intervention. The hemoglobin level mean was increased among the studied pregnant women after educational instructions intervention. Conclusion: Educational instruction intervention has a positive effect on enhancing pregnant women's knowledge and practice regarding iron deficiency anemia and hemoglobin level. Recommendations: Educational instruction intervention is recommended in various maternity healthcare settings. Educational booklets should be provided about foods with a high concentration of iron to reduce iron deficiency anemia in pregnant women