Caring is considered as the essence of nursing and is the basic factor that distinguishes between nurses and other health professions. The literature is rich of previous studies that focused on perceptions of nurses toward nurse caring behaviors, but less studywas applied in pediatric nurses in different settings. Aim of the study:evaluate the effect of application of Watson caring theory for nurses in pediatric critical care unit. Method(s): A convenience sample of 70 nurses of Pediatric Critical Care Unit in El-Menoufya University Hospital and educational hospital in ShebenElkom.were completed the demographics questionnaire, and the Caring Behavior Assessment (CBA) questionnaire,medical record to collect medical data regarding children characteristics such as age and diagnosis, Interviewing questionnaire for nurses regarding their barrier to less interest of comfort behavior such as doing doctor order, Shortage of nursing staff, Large number of patients, Heavy workloads, Secretarial jobs for nurses and Emotional stress. Results: more thantwothirds of nurses in study group and majority of control group had age less than 30 years, there were highly statistically significant difference related to mean scores for Caring Behavior Assessment (CBA) as rated by nurses in pretest (1.4750 to 2.0750) than in posttest (3.5 to 4.55). Also, near to two-thirds (64.3%) of the nurses stated that doing doctor order act as a barrier to apply this theory. In addition, there were a statistical significance difference between educational qualifications of nurses and a Supportive\ protective\corrective environment subscale with mean score for master degree 57.0000, also between years of experiences and human needs assistance. Conclusion: Program instructions for all nurses to apply Watson Caring theory for children in pediatric critical care unit were successful and effective and this study provided evidence for application of this theory for different departments in all settings. Recommendations: It was recommended that In-service training programs for nurses about caring behavior and its different areas, with special emphasis on communication are needed to improve their own behaviors in all aspects of the caring behaviors for all health care settings. Motivating hospital authorities to recruit more nurses, then, the nurses would be able to have more care that is direct. Consequently, the amount and the quality of nurse-child communication and opportunities for patient education would increase, this in turn improve child's outcome.