Arterial blood gases sampling is a valuable tool in the assessment of multitude of illness and injuries. It represents the criterion stander for determining a ventilated and non- ventilated children's acid base status. Aim of the study was to evaluate the effect of educational program on improving nurses' performance regarding arterial blood gases sampling for critically ill children. Setting: The study was conducted at pediatric intensive care units in Benha University hospital and Benha Specialized pediatric hospital. Design: A quasi experimental design was utilized for conducting the current study. Sample: A convenient sample of (50) nurses working at the above mentioned settings were recruited for this study regardless of their personal characteristics.Tools: Two tools were used for data collection, a structured questionnaire sheet to assess nurses' knowledge about arterial blood gases sampling and an observational checklist to assess nurses ' practice regarding arterial blood gases sampling. Results: There was a highly statistical significant differences in nurses' knowledge and practice regarding arterial blood gases sampling before and after program implementation. Conclusion:Based on the results of the present study, it can be concluded that, the research hypothesis is accepted, while it was found that the educational program is highly effective method to improve the nurses' knowledge and practice regarding arterial blood gases sampling.Recommendation:The study recommended that, the continuous training and evaluating should be provided to all nurses involved in arterial blood gases sampling in order to update their knowledge and ensure competent practice.