Background: Iatrogenic events that cause harm to neonates in NICU is characterized as adverse events. Neonates are a particularly vulnerable population and may be at further risk of harm from medical errors because of their low birth weight, physiological immature, limited compensatory abilities and extensive exposure to medication in NICU. Nurses are the first line of defense to safeguard against iatrogenic errors. Aim of this study was to evaluated the effect of educational intervention program on nurses' performance and clinical outcomes of neonates related to nurses' iatrogenic at neonatal intensive care unit. Subjects and method The study was conducted at Neonatal Intensive Care Unit of Tanta University hospital. A quasi-experimental design was used. Sample All nurses (57) working in the previously mentioned setting were included the study and all neonates admitted within six months. Tools: Three tools were used to collect the required data; Structured Interview schedule, It was consisted of two parts, part one was biosocial data of nurses, neonate and part two was nurses' knowledge (tool I). Observation checklist to assess nurse's practice regarding iatrogenic errors at NICU (tool II). Neonate's clinical outcomes schedule to assess outcomes of neonate post program (tool III). Results of the study revealed that, before program the total knowledge scores of all nurses were poor while majority of them had good scores after implementing program. Total practice scores of all nurses were good also immediately and after one month. There were statistical significant difference between nursing knowledge, practice and biosocial data. The outcome of neonates showed an improvement in neonatal condition of discharge. Conclusion Intervention program was effective and improving nurses' knowledge and practice as well as reducing iatrogenic errors at NICU. Recommendations were suggested that establish continuous monitoring system to assess nurses practice in NICU settings especially for iatrogenic errors