Background: Fluids and electrolytes imbalances are the most frequently reported problems in urinary diversion patients. The nurse plays a major role through identifying causes, manifestation and management of this problem. Moreover life threatening nature of theses imbalances makes nurses a particularly important area for nursing assessment and care. Aim of the study was to assess nurses' role regarding care of patients with fluid and electrolyte imbalance undergoing urinary diversion. Subjects and methods: Research design: A descriptive design was utilized to achieve aim of the study. Setting: The study was conducted in the urology department at Zagazig University and Al-Ahrar Hospitals at Zagazig City in Sharkia Government, Egypt. Subjects: A convenience sample of all available (50) nurses were recruited from the urology department at Zagazig University and Al-Ahrar Hospitals. Tools of data collection: Two tools were used to collect the study data. Tool I: An Interview nurses questionnaire which included personal characteristics of studied nurses, questions to assess nurses` knowledge, and Tool II: An observational checklist to assess nurses` practices. Results: The present study revealed that 78.0% of studied nurses had an unsatisfactory level of total knowledge score while 82.0% of them had an unsatisfactory level of total practice score Conclusion: There was positive significant correlation between total knowledge score of the studied nurses and total practice score. Recommendation: in service training programs for updating the knowledge and practice of nurses working in urology department for early identification and management of patients with fluid and electrolyte imbalance undergoing urinary diversion. Further study is necessary to identify effect of educational program on nurses' performance at urology department and emphasizing evidence – based practices. Keywords: Nurses role, Fluid, Electrolytes Imbalance &, Urinary Diversion Patient.