Background: The role of critical care nurse in arrhythmias management specializes in symptomatic relief, promotion of comfort and taking crisis activity in fatal dysrhythmias. Aim: The aim of the study was to evaluate the effect of nursing training program on nurses' knowledge and practice regarding the care of patient with cardiac arrhythmias in Cardiac Intensive Care units at Zagazig University Hospitals, Egypt. Subjects and Methods: Research design: A quazi experimental design was utilized to achieve the aim of this study. Setting: The study was conducted in Cardiac Intensive Care Units at Zagazig University Hospitals. Sample: A convenient sample of all available nurses (30 nurses) was included in this study. Tools of data collection: Self-administered questionnaire and observational checklists were used. Data were collected over a period of nine months. Results: There was statistically significant difference in total level of nurses' knowledge, and practice pre, post and post, follow-up phases of nursing training program. Conclusion: The nursing training program had a significant positive effect on improving nurses' knowledge, and practice regarding care of patients with cardiac arrhythmias. Recommendations: It was recommended periodic evaluation of nurses' knowledge and practice concerning management of patients in any emergency situation in the critical care units.