Introduction: Preoperative renal function assessment is a prerequisite for many surgical procedures. This is because of the vital function of the kidneys in the regulation of serum electrolytes, and excretion of waste products or by-products of metabolic processes. Materials and Methods: This cross-sectional descriptive study was done at two university teaching hospitals in Port Harcourt, Nigeria, from January 2021 to December 2022. Case files of seventy-two (72) women scheduled for major gynecological surgeries were studied. Data obtained were analyzed using the SPSS, version 20, and the outcome was expressed using frequency tables and charts. Results: The mean age of the women in the study was 37.50 ± 1.22 years. Women with hyponatremias were 9 (12.5%); hypokalemia, 11 (15.3%); hyperkalemia, 3 (4.2%). Thirty-nine patients, 39 (54.2%) had acidosis, low serum bicarbonate (HCO3-). Low blood urea was found in 11 (15.3%) of the women. One of them (1.4%) had elevated blood urea. The rest had normal values. Hypocreatinaemia and hypercreatinaemia were detected in 29 (40.3%) and 2 (2.8%) patients respectively. Conclusion: Electrolyte derangement was found in 40 (55.6%) of the patients preoperatively. This finding suggests that renal function assessment is crucial in the preoperative evaluation of gynecological patients before major gynecological surgeries.