Background: Nurses' knowledge and practice could be beneficial in caring for patients with implantable cardiac devices and preventing any self or environmental interactions which can adversely affect proper device function. Aim of the Study: To assess nurses' performance for patients with implantable cardiac devices. Research Design: A descriptive exploratory design was utilized. Setting: This study was conducted at the cardiac care units and intermediate cardiac care units at Ain Shams University Hospital. Subjects: A convenience sample of all available nurses (50) working within the previous mentioned setting was included in the study. Tools: Nurses' self-administered questionnaire which composed of nurses' demographic characteristics, nurses' level of knowledge and factors affecting nurses' performance regarding care of patients with implantable cardiac devices. Nurses' practice observational checklist. Results: The present study revealed that 66% of nurses under the study had a satisfactory level of total knowledge regarding care of patients with implantable cardiac devices, 62% of studied nurses had agreed that the work environment, nurse and patient related factors affect their performance and 58% of studied nurses had a competent level of total practice. Conclusion: This study concluded that there was a highly statistically significant with positive correlation between total nurses' level of knowledge and total nurses' level of practice regarding care of patients with implantable cardiac devices. Recommendations: Replication of the current study on a larger probability sample selected from different geographical areas in Egypt to achieve generalization of the results.