Thrombotic occlusion of saphenous vein grafts (SVG), the conduits most commonly used in coronary artery bypass grafting (CABG) surgery, causes significant morbidity and mortality. There is class 1A evidence that early aspirin administration following CABG reduces thrombotic SVG occlusion, as well as overall morbidity and mortality. The American Heart Association/American College of Cardiology and the European Association of Cardiothoracic Surgeons have issued guidelines recommending that 150 to 325 mg aspirin be administered within 6 hours following CABG. We carried out a clinical audit of our practice to identify any reasons for deviation from these standards of care and to implement any corrective measures. We prospectively collected data on 200 consecutive patients who underwent CABG to assess both the compliance in prescribing and administering aspirin and the effect on blood loss and transfusion requirements. Sixty-nine percent of patients received an aspirin loading dose 6 hours postoperatively. The reasons for nonadministration of aspirin were postoperative bleeding (10%), lack of a prescription despite aspirin being clinically indicated (13%), and a prescription for aspirin but no administration (9%). Reasons included inadequate handover between clinical teams (4%), aspirin loading ≤24 hours preoperatively (2%), and administration after the first 6 hours (3%). Our audit showed that early aspirin administration did not cause further bleeding or increase blood or blood product transfusion. We followed the recommendations in the majority of cases, but there is scope for improvement in this practice and a need to address "gray areas" not covered by the guidelines.