Background: Urinary catheterization is an invasive procedure carried out by nurses as part of the routine of their care practice. Hence, professional must have knowledge related to the management of urinary catheterization. Aim of the study was to evaluate the impact of protocol of care of patients undergoing urinary catheterization on nurses, practice. Subject and Method: A quasi- experimental research design was used to conduct this study. The study was carried out at Intensive Care Unit, Urology Department and Department of Internal Medicine at Al-Azhar University hospital in Damietta City to test the hypotheses that positive changes in nurses' practice after implementing the protocol of care for patients undergoing urinary catheterization. A convenient sample of 50 nurses was included. One tool was used for data collections, part (1) Structured Interview Questionnaire tool that includes demographic data part (2) Observational Checklist to evaluate nurses' practice in relation to care of patient patients undergoing urinary catheterization Results demonstrated that there were statistically significant improvements in the total score of nurses' practice regarding care of patients undergoing urinary catheterization throughout the protocol intervention. Recommendations: The study recommended that providing ongoing inservice education for nurses to update their practice related to care of patients undergoing urinary catheterization and catheter –associated problems.