Background: Reflection is a recent trend in  medical  and  nursing education whether in teaching or treating. Reflecting on experiences allowed connections to be made between thoughts, beliefs, and actions. Aim: This study was aimed to evaluate the impact of reflective thinking intervention on improving nursing care given by nurses in pediatric critical care  units.  Setting:  The  study  was conducted at pediatric critical care units affiliated to Ain shams university hospitals. Subject and methods: The subjects of the study composed of 55 nurses and all available children at the previously mentioned setting. Three types of tools were used to collect data; an interviewing questionnaire sheet,  nursing  core  competencies clinical evaluation tool & nurses’ achievements tests.  Results:  Nearly one quarter of the studied nurses had competent level  of  nursing  core  competencies  through nurses′ reflection pre intervention compared to more than three quarters post intervention. Conclusion: There was a positive impact of reflective thinking intervention on improving pediatric nursing care. Recommendation: Encouraging linkage of nurses’ performance appraisal to the extent of their use  of  reflective thinking in order to increase their core competencies during care of the pediatric patient at critical care unites.