Background: The most effective method for identifying and treating coronary artery disease is cardiac catheterization. One of the most important components of providing healthcare in all contexts is ensuring patient safety. Patients' lives can be saved by spotting any shortcomings in care and raising nurses' understanding of their crucial role. Aim: To evaluate the effect of implementing educational guidelines on cardiac nurses' performance regarding patient safety post-cardiac catheterization. Design: A quasi-experimental research design was used. Setting: The study was conducted in the cardiac catheterization unit, and cardiac care unit at Mania University Hospital. Sample: A purposive sample of all available nurses and 50 nurses who are working in the selected setting. Tools: Four tools were used for data collection: nurses' personal demographic data, nurses' knowledge concerning safety measures, a safety measures observational checklist and  A safety attitude questionnaire. Results: There was a highly statistically significant improvement in nurses' total knowledge, attitude, and practices mean score in post post-educational guidelines implementation phase than the pre-educational guidelines phase concerning safety measures. A statistically significant correlation was found between total practices, total knowledge, and attitude among the studied nurses (p ≤ 0.05). Conclusion: The study's findings conclude that educational guidelines implementation has a positive effect on improving cardiac nurses' performance regarding patient safety post-cardiac catheterization. Recommendations: The study recommends that nurses working in cardiac catheterization units continuously engage in educational programs to improve their nurses' knowledge and practical skills regarding safety measures concepts.