Coronary artery bypass grafting (CABG) is a major cardiac surgery associated with risks of serious perioperative complications and mortality. Malnutrition and inflammation are known independent risk factors for poor outcomes in patients with coronary artery disease. This retrospective observational study evaluates the Prognostic Nutritional Index (PNI)-a simple score derived from serum albumin and lymphocyte counts-as an objective measure of nutritional and inflammatory status. The research aims to determine how well preoperative PNI and its postoperative changes can predict complications such as acute kidney injury, myocardial infarction, and sternal wound infections in patients undergoing CABG.