Objectives: To determine the impact of preoperative serum creatinine level in non-dialyzable patients on postoperative morbidity and mortality. Methods: This is a prospective study, where serum creatinine was used to give primary assessment on renalfunction status preoperatively. This study includes 1,033patients, who underwent coronary artery bypass grafting,or valve(s) operations. The study took place at Al-Hada Military Hospital, Taif, Kingdom of Saudi between May 2008 and January 2012. Data were statistically analyzed using Chi square (χ2) test and multivariable logistic regression, to evaluate the postoperative morbidity and mortality risks associated with low serum creatinine levels.Results: Postoperative mortality increased with high serum creatinine level >1.8 mg/dL (p≤0.0005). Multivariable logistic regression, adjusting for potentially confounding variables demonstrated that a creatinine level of more than 1.8mg/dL was associated with increased risk of re-operation for bleeding, postoperative renal failure, prolonged ventilatory support, ICU stay, and total hospital stay. Conclusions: Perioperative serum creatinine is strongly related to post operative morbidity and mortality in open heart surgery. High serum creatinine in non-dialyzable patients can predict the increased morbidity and mortality after cardiac operations.